diff --git a/src/downloader/mod.rs b/src/downloader/mod.rs
new file mode 100644
index 0000000..610a386
--- /dev/null
+++ b/src/downloader/mod.rs
@@ -0,0 +1 @@
+pub mod pd_file;
diff --git a/src/downloader/pd_file/enums.rs b/src/downloader/pd_file/enums.rs
new file mode 100644
index 0000000..c4ecdc3
--- /dev/null
+++ b/src/downloader/pd_file/enums.rs
@@ -0,0 +1,45 @@
+use int_enum::IntEnum;
+
+/// The status of the downloaded file.
+#[repr(u8)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, IntEnum)]
+pub enum PdFileStatus {
+    /// The download is already started but the target size is unknown.
+    Started = 0,
+    /// The download is started and the tagret size is known.
+    Downloading = 1,
+    /// The download is completed.
+    Downloaded = 2,
+}
+
+impl PdFileStatus {
+    #[inline]
+    /// Returns true if the download is completed.
+    pub fn is_completed(&self) -> bool {
+        *self == PdFileStatus::Downloaded
+    }
+}
+
+/// The type of the downloader.
+#[repr(u8)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, IntEnum)]
+pub enum PdFileType {
+    /// Download in single thread mode.
+    SingleThread = 0,
+    /// Download in multiple thread mode.
+    MultiThread = 1,
+}
+
+impl PdFileType {
+    #[inline]
+    /// Returns true if is multiple thread mode.
+    pub fn is_multi(&self) -> bool {
+        *self == PdFileType::MultiThread
+    }
+}
+
+#[test]
+fn test_enums() {
+    assert_eq!(PdFileStatus::Downloading.int_value().to_le_bytes(), [1]);
+    assert_eq!(PdFileType::MultiThread.int_value().to_le_bytes(), [1]);
+}
diff --git a/src/downloader/pd_file/error.rs b/src/downloader/pd_file/error.rs
new file mode 100644
index 0000000..f1bfa43
--- /dev/null
+++ b/src/downloader/pd_file/error.rs
@@ -0,0 +1,30 @@
+use crate::gettext;
+use std::convert::From;
+use std::fmt::Display;
+
+#[derive(Debug, derive_more::From)]
+pub enum PdFileError {
+    IoError(std::io::Error),
+    String(String),
+}
+
+impl Display for PdFileError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::IoError(e) => {
+                f.write_str(gettext("Errors occured when operating files: "))?;
+                e.fmt(f)?;
+            }
+            Self::String(e) => {
+                f.write_str(e)?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl From<&str> for PdFileError {
+    fn from(value: &str) -> Self {
+        PdFileError::String(String::from(value))
+    }
+}
diff --git a/src/downloader/pd_file/file.rs b/src/downloader/pd_file/file.rs
new file mode 100644
index 0000000..8eb1d69
--- /dev/null
+++ b/src/downloader/pd_file/file.rs
@@ -0,0 +1,222 @@
+use crate::downloader::pd_file::error::PdFileError;
+use crate::downloader::pd_file::enums::PdFileStatus;
+use crate::downloader::pd_file::enums::PdFileType;
+use crate::downloader::pd_file::version::PdFileVersion;
+use crate::ext::rw_lock::GetRwLock;
+use crate::ext::try_err::TryErr;
+use crate::ext::try_err::TryErr2;
+use crate::gettext;
+use int_enum::IntEnum;
+use std::convert::AsRef;
+use std::fs::File;
+#[cfg(test)]
+use std::fs::metadata;
+use std::fs::remove_file;
+use std::io::Seek;
+use std::io::SeekFrom;
+use std::io::Write;
+use std::ops::Drop;
+use std::path::Path;
+use std::path::PathBuf;
+use std::sync::RwLock;
+use std::sync::atomic::AtomicBool;
+use std::sync::atomic::AtomicU32;
+use std::sync::atomic::AtomicU64;
+use std::sync::atomic::Ordering;
+
+lazy_static! {
+    #[doc(hidden)]
+    static ref MAGIC_WORDS: Vec<u8> = vec![0x50, 0x44, 0xff, 0xff];
+}
+
+/// The pd file
+pub struct PdFile {
+    /// The version of the current file.
+    version: PdFileVersion,
+    /// Needed to save to file.
+    need_saved: AtomicBool,
+    /// The file handle of the pd file.
+    file: RwLock<Option<File>>,
+    /// The file path of the pd file.
+    file_path: RwLock<Option<PathBuf>>,
+    /// The file name
+    file_name: RwLock<Option<String>>,
+    /// The status of the downloaded file.
+    status: RwLock<PdFileStatus>,
+    /// The type of the downloader.
+    ftype: RwLock<PdFileType>,
+    /// The target size of the file. If unknown, set this to 0.
+    file_size: AtomicU64,
+    /// The size of the downloaded data.
+    downloaded_file_size: AtomicU64,
+    /// The size of the each part. Ignored in single thread mode.
+    part_size: AtomicU32,
+}
+
+impl PdFile {
+    /// Create a new instance of the [PdFile]
+    pub fn new() -> Self {
+        Self {
+            version: PdFileVersion::new(1, 0),
+            need_saved: AtomicBool::new(false),
+            file: RwLock::new(None),
+            file_path: RwLock::new(None),
+            file_name: RwLock::new(None),
+            status: RwLock::new(PdFileStatus::Started),
+            ftype: RwLock::new(PdFileType::SingleThread),
+            file_size: AtomicU64::new(0),
+            downloaded_file_size: AtomicU64::new(0),
+            part_size: AtomicU32::new(0),
+        }
+    }
+
+    /// Close the file.
+    /// This function will return error if write failed.
+    /// If you want to force close the file. Please use [Self::force_close()].
+    pub fn close(&self) -> Result<(), PdFileError> {
+        if self.is_need_saved() {
+            self.write()?;
+        }
+        self.force_close();
+        Ok(())
+    }
+
+    /// Force close the file
+    pub fn force_close(&self) {
+        let mut f = self.file.get_mut();
+        match f.as_mut() {
+            Some(_) => { f.take(); }
+            None => {}
+        }
+    }
+
+    #[inline]
+    /// Returns true if the download is completed.
+    pub fn is_completed(&self) -> bool {
+        self.status.get_ref().is_completed()
+    }
+
+    #[inline]
+    /// Returns true if needed to save to file.
+    fn is_need_saved(&self) -> bool {
+        self.need_saved.load(Ordering::Relaxed)
+    }
+
+    /// Create a new file and prepare to write data to it.
+    /// If file alreay exists, will remove it first.
+    /// * `path` - The path to the pd file.
+    pub fn open_with_create_file<P: AsRef<Path> + ?Sized>(&self, path: &P) -> Result<(), PdFileError> {
+        let p = path.as_ref();
+        if p.exists() {
+            remove_file(p)?;
+        }
+        let f = File::create(p)?;
+        self.file.get_mut().replace(f);
+        self.file_path.get_mut().replace(PathBuf::from(p));
+        self.need_saved.store(true, Ordering::Relaxed);
+        Ok(())
+    }
+
+    /// Remove file in [Self::file_path]
+    fn remove_pd_file(&self) -> Result<(), PdFileError> {
+        match self.file_path.get_ref().as_ref() {
+            Some(pb) => {
+                if pb.exists() {
+                    remove_file(pb)?;
+                }
+                Ok(())
+            }
+            None => { Ok(()) }
+        }
+    }
+
+    /// Remove file in [Self::file_path] and if error occered print that error.
+    fn remove_pd_file_with_err_msg(&self) {
+        match self.remove_pd_file() {
+            Ok(_) => {}
+            Err(e) => {
+                println!("{} {}", gettext("Failed to remove file: "), e);
+            }
+        }
+    }
+
+    /// Set the file name
+    /// * `file_name` - The file name. Should not be empty.
+    pub fn set_file_name<S: AsRef<str> + ?Sized>(&self, file_name: &S) -> Result<(), PdFileError> {
+        let fname = file_name.as_ref();
+        if fname.is_empty() {
+            Err(gettext("File name should not be empty."))?
+        } else {
+            self.file_name.get_mut().replace(String::from(fname));
+            self.need_saved.store(true, Ordering::Relaxed);
+            // Rewrite all datas.
+            self.write()?;
+            Ok(())
+        }
+    }
+
+    /// Write all data to the file.
+    pub fn write(&self) -> Result<(), PdFileError> {
+        let mut f = self.file.get_mut();
+        let mut f = f.as_mut().try_err(gettext("The file is not opened."))?;
+        f.seek(SeekFrom::Start(0))?;
+        f.write_all(&MAGIC_WORDS)?;
+        self.version.write_to(&mut f)?;
+        let file_name = self.file_name.get_ref().try_err2(gettext("File name is not set."))?;
+        let file_name = file_name.as_bytes();
+        f.write_all(&(file_name.len() as u32).to_le_bytes())?;
+        f.write_all(&self.status.get_ref().int_value().to_le_bytes())?;
+        let ftype = self.ftype.get_ref();
+        f.write_all(&ftype.int_value().to_le_bytes())?;
+        f.write_all(&self.file_size.load(Ordering::Relaxed).to_le_bytes())?;
+        f.write_all(&self.downloaded_file_size.load(Ordering::Relaxed).to_le_bytes())?;
+        let part_size = if ftype.is_multi() {
+            self.part_size.load(Ordering::Relaxed)
+        } else {
+            0
+        };
+        f.write_all(&part_size.to_le_bytes())?;
+        f.write_all(file_name)?;
+        self.need_saved.store(false, Ordering::Relaxed);
+        Ok(())
+    }
+}
+
+impl Drop for PdFile {
+    fn drop(&mut self) {
+        if self.is_completed() {
+            self.force_close();
+            self.remove_pd_file_with_err_msg();
+            return;
+        }
+        if self.is_need_saved() {
+            match self.write() {
+                Ok(_) => {}
+                Err(e) => {
+                    println!("{}", e);
+                    self.force_close();
+                    self.remove_pd_file_with_err_msg();
+                }
+            }
+        };
+        self.force_close();
+    }
+}
+
+#[cfg(test)]
+fn check_file_size<P: AsRef<Path> + ?Sized>(path: &P, size: u64) -> Result<(), PdFileError> {
+    let m = metadata(path)?;
+    assert!(m.len() == size);
+    Ok(())
+}
+
+#[test]
+fn test_pd_file() -> Result<(), PdFileError> {
+    {
+        let f = PdFile::new();
+        f.open_with_create_file("test/a.pd")?;
+        f.set_file_name("a")?;
+    }
+    check_file_size("test/a.pd", 33)?;
+    Ok(())
+}
diff --git a/src/downloader/pd_file/mod.rs b/src/downloader/pd_file/mod.rs
new file mode 100644
index 0000000..ff1b856
--- /dev/null
+++ b/src/downloader/pd_file/mod.rs
@@ -0,0 +1,8 @@
+/// The error type of the pd file.
+pub mod error;
+/// The pd file
+pub mod file;
+/// The enums of the pd file.
+pub mod enums;
+/// Version of the pd file
+pub mod version;
diff --git a/src/downloader/pd_file/version.rs b/src/downloader/pd_file/version.rs
new file mode 100644
index 0000000..0b7a82d
--- /dev/null
+++ b/src/downloader/pd_file/version.rs
@@ -0,0 +1,129 @@
+use std::cmp::Ord;
+use std::cmp::Ordering;
+use std::cmp::PartialEq;
+use std::cmp::PartialOrd;
+use std::convert::AsRef;
+use std::convert::TryFrom;
+use std::io::Write;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+/// Version of the pd file
+pub struct PdFileVersion {
+    /// Major verson
+    major: u8,
+    /// Minor version
+    minor: u8,
+}
+
+impl PdFileVersion {
+    /// Create a new instance of the [PdFileVersion]
+    /// * `major` - major version
+    /// * `minor` - minor version
+    pub fn new(major: u8, minor: u8) -> Self {
+        Self { major, minor }
+    }
+
+    /// Create a new instance of the [PdFileVersion] from bytes.
+    /// * `bytes` - The data
+    /// * `offset` - The offset of the needed data
+    /// 
+    /// Returns a new instance if succeed otherwise a Error because the data is less than 2 bytes.
+    pub fn from_bytes<T: AsRef<[u8]> + ?Sized>(bytes: &T, offset: usize) -> Result<Self, ()> {
+        let value = bytes.as_ref();
+        if (value.len() - offset) < 2 {
+            Err(())
+        } else {
+            Ok(Self::new(value[offset], value[offset + 1]))
+        }
+    }
+
+    /// Get version bytes
+    pub fn to_bytes(&self) -> Vec<u8> {
+        let mut data = Vec::new();
+        data.push(self.major);
+        data.push(self.minor);
+        data
+    }
+
+    /// Write version bytes to writer.
+    /// * `writer` - The writer which implement the [Write] trait
+    /// 
+    /// Returns io Result.
+    pub fn write_to<W: Write>(&self, writer: &mut W) -> std::io::Result<()> {
+        writer.write_all(&self.to_bytes())
+    }
+}
+
+impl TryFrom<&[u8]> for PdFileVersion {
+    type Error = ();
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        Self::from_bytes(value, 0)
+    }
+}
+
+impl Ord for PdFileVersion {
+    fn cmp(&self, other: &Self) -> Ordering {
+        let r = self.major.cmp(&other.major);
+        if r.is_eq() {
+            self.minor.cmp(&other.minor)
+        } else {
+            r
+        }
+    }
+}
+
+impl PartialOrd for PdFileVersion {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        let r = self.major.cmp(&other.major);
+        if r.is_eq() {
+            Some(self.minor.cmp(&other.minor))
+        } else {
+            Some(r)
+        }
+    }
+}
+
+/// # Note
+/// If [Self::from_bytes()] returns error, assert it to false.
+impl<T: AsRef<[u8]> + ?Sized> PartialEq<T> for PdFileVersion {
+    fn eq(&self, other: &T) -> bool {
+        match Self::from_bytes(other, 0) {
+            Ok(v) => { v == *self }
+            Err(_) => { false }
+        }
+    }
+}
+
+/// # Note
+/// If [Self::from_bytes()] returns error, assert it to false.
+impl<T: AsRef<[u8]> + ?Sized> PartialOrd<T> for PdFileVersion {
+    fn partial_cmp(&self, other: &T) -> Option<Ordering> {
+        match Self::from_bytes(other, 0) {
+            Ok(v) => { Some(self.cmp(&v)) }
+            Err(_) => { None }
+        }
+    }
+}
+
+#[test]
+fn test_pd_file_version() {
+    assert!(PdFileVersion::new(1, 0) != PdFileVersion::new(0, 1));
+    assert!(PdFileVersion::new(1, 10) != PdFileVersion::new(11, 0));
+    assert!(PdFileVersion::new(1, 10) == PdFileVersion::new(1, 10));
+    assert!(PdFileVersion::from_bytes(&vec![1, 10], 0).unwrap() == PdFileVersion::new(1, 10));
+    assert_eq!(PdFileVersion::new(1, 10).to_bytes(), vec![1, 10]);
+    assert!(PdFileVersion::new(2, 1) > PdFileVersion::new(1, 3));
+    assert!(PdFileVersion::new(1, 3) > PdFileVersion::new(1, 2));
+    assert!(PdFileVersion::new(3, 2) >= PdFileVersion::new(3, 2));
+    assert!(PdFileVersion::new(1, 4) < PdFileVersion::new(1, 11));
+    assert!(PdFileVersion::new(1, 3) < PdFileVersion::new(2, 1));
+    assert!(PdFileVersion::new(1, 2) == [1u8, 2]);
+    assert!(PdFileVersion::new(1, 3) == vec![1u8, 3, 2]);
+    assert!(PdFileVersion::new(1, 2) == [1, 2, 3]);
+    assert!(PdFileVersion::new(1, 3) == vec![1, 3, 2]);
+    assert!(PdFileVersion::new(1, 2) != [1]);
+    assert!(PdFileVersion::new(2, 3) > [1, 10]);
+    assert!(PdFileVersion::new(3, 1) < [10, 1]);
+    assert!(PdFileVersion::new(3, 3) >= [3, 3]);
+    assert!(!(PdFileVersion::new(2, 3) > [1]))
+}
diff --git a/src/ext/try_err.rs b/src/ext/try_err.rs
index f098aa6..13a1c80 100644
--- a/src/ext/try_err.rs
+++ b/src/ext/try_err.rs
@@ -1,14 +1,29 @@
+/// Try with custom error message
+pub trait TryErr2<T, E> {
+    /// try with custom error message
+    fn try_err2(&self, err: E) -> Result<T, E>;
+}
+
 /// Try with custom error message
 pub trait TryErr<T, E> {
     /// try with custom error message
-    fn try_err(&self, err: E) -> Result<T, E>;
+    fn try_err(self, err: E) -> Result<T, E>;
 }
 
-impl<T: ToOwned + ToOwned<Owned = T>, E> TryErr<T, E> for Option<T> {
-    fn try_err(&self, v: E) -> Result<T, E> {
+impl<T: ToOwned + ToOwned<Owned = T>, E> TryErr2<T, E> for Option<T> {
+    fn try_err2(&self, v: E) -> Result<T, E> {
         match self {
             Some(r) => { Ok(r.to_owned()) }
             None => { Err(v) }
         }
     }
 }
+
+impl<T, E> TryErr<T, E> for Option<T> {
+    fn try_err(self, err: E) -> Result<T, E> {
+        match self {
+            Some(v) => { Ok(v) }
+            None => { Err(err) }
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 76804a6..6aab259 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -36,6 +36,7 @@ mod avdict;
 mod cookies;
 mod data;
 mod download;
+mod downloader;
 mod dur;
 #[cfg(feature = "exif")]
 /// Used to read/modify image's exif data