diff --git a/src/commands/add.rs b/src/commands/add.rs
index edba0d1..256238d 100644
--- a/src/commands/add.rs
+++ b/src/commands/add.rs
@@ -1,9 +1,10 @@
 use std::env;
 use std::path::{Path, PathBuf};
 use colored::Colorize;
+use sha1::Digest;
 use crate::models::blob::Blob;
 use crate::models::index::{FileMetaData, Index};
-use crate::utils::util::{check_repo_exist, get_file_mode, get_relative_path, get_working_dir, list_files};
+use crate::utils::util::{check_repo_exist, get_relative_path, get_working_dir, list_files};
 
 pub fn add(files: Vec<String>, all: bool, mut update: bool) {
     check_repo_exist();
@@ -41,23 +42,21 @@ pub fn add(files: Vec<String>, all: bool, mut update: bool) {
     for file in &files {
         add_a_file(file, &mut index);
     }
+
+    index.save();
 }
 
 fn add_a_file(file: &Path, index: &mut Index) {
     println!("add a file: {}", get_relative_path(file, get_working_dir().unwrap()).display());
     if !file.exists() { //文件被删除
         index.remove(file);
-    } else if !index.contains(file) { //文件未被跟踪
+    } else {
         let blob = Blob::new(file);
-        let meta = file.metadata().unwrap();
-        index.add(file.to_path_buf(), FileMetaData{
-            hash: blob.get_hash(),
-            size: meta.len(),
-            created_time: meta.created().unwrap(),
-            modified_time: meta.modified().unwrap(),
-            mode: get_file_mode(file)
-        });
-    } else { //文件已被跟踪，可能被修改
-
+        let file_data = FileMetaData::new(&blob, file);
+        if !index.contains(file) { //文件未被跟踪
+            index.add(file.to_path_buf(), file_data);
+        } else { //文件已被跟踪，可能被修改
+            index.update(file.to_path_buf(), file_data);
+        }
     }
 }
\ No newline at end of file
diff --git a/src/models/blob.rs b/src/models/blob.rs
index c3fc7fc..4f23967 100644
--- a/src/models/blob.rs
+++ b/src/models/blob.rs
@@ -15,10 +15,13 @@ pub struct Blob {
 }
 
 impl Blob {
+    /// 从源文件新建blob对象，并直接保存到/objects/中
     pub fn new(file: &Path) -> Blob {
         let data = fs::read_to_string(file).unwrap();
         let hash = calc_hash(&data);
-        Blob { hash, data }
+        let blob = Blob { hash, data };
+        blob.save();
+        blob
     }
 
     pub fn load(hash: &String) -> Blob {
@@ -32,7 +35,10 @@ impl Blob {
 
     pub fn save(&self) {
         let s = Store::new();
-        s.save(&self.data);
+        if !s.contains(&self.hash) {
+            let hash = s.save(&self.data);
+            assert_eq!(hash, self.hash);
+        }
     }
 
     pub fn get_hash(&self) -> String {
diff --git a/src/models/index.rs b/src/models/index.rs
index 916d62a..57ccd4f 100644
--- a/src/models/index.rs
+++ b/src/models/index.rs
@@ -3,8 +3,9 @@ use std::fs;
 use std::path::{Path, PathBuf};
 use std::time::SystemTime;
 use serde::{Deserialize, Serialize};
+use crate::models::blob::Blob;
 use crate::models::object::Hash;
-use crate::utils::util::get_working_dir;
+use crate::utils::util::{get_file_mode, get_working_dir};
 
 // 文件元数据结构
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -16,6 +17,19 @@ pub struct FileMetaData {
     pub mode: String,                 // 文件模式
 }
 
+impl FileMetaData {
+    pub fn new(blob: &Blob, file: &Path) -> FileMetaData {
+        let meta = file.metadata().unwrap();
+        FileMetaData {
+            hash: blob.get_hash(),
+            size: meta.len(),
+            created_time: meta.created().unwrap(),
+            modified_time: meta.modified().unwrap(),
+            mode: get_file_mode(file)
+        }
+    }
+}
+
 // 索引数据结构
 #[derive(Serialize, Deserialize, Debug, Default)]
 pub struct Index {
@@ -69,12 +83,16 @@ impl Index {
         files
     }
 
+    pub fn update(&mut self, path: PathBuf, data: FileMetaData) {
+        self.entries.insert(path, data);
+    }
+
     fn load(&mut self) {
 
     }
 
     /// 二进制序列化
-    fn save(&self) { //要先转化为相对路径
+    pub fn save(&self) { //要先转化为相对路径
         let ser = serde_json::to_string(&self).unwrap();
         println!("{}", ser);
     }
@@ -97,8 +115,9 @@ mod tests {
 
     #[test]
     fn test_save(){
+        util::setup_test_with_mit();
         let mut index = Index::new();
-        let metadata = fs::metadata(".gitignore").unwrap();
+        let metadata = fs::metadata("../.gitignore").unwrap();
         let file_meta_data = FileMetaData {
             hash: "123".to_string(),
             size: metadata.len(),
diff --git a/src/store.rs b/src/store.rs
index a0c4e66..8e3702f 100644
--- a/src/store.rs
+++ b/src/store.rs
@@ -24,6 +24,14 @@ impl Store {
             Err(_) => panic!("储存库疑似损坏，无法读取文件"),
         }
     }
+
+    pub fn contains(&self, hash: &String) -> bool {
+        let mut path = self.store_path.clone();
+        path.push("objects");
+        path.push(hash);
+        path.exists()
+    }
+
     pub fn save(&self, content: &String) -> String {
         /* 保存文件内容 */
         println!("store_path: {:?}", self.store_path);
@@ -41,7 +49,6 @@ impl Store {
 }
 #[cfg(test)]
 mod tests {
-
     use super::*;
 
     #[test]