diff --git a/Cargo.toml b/Cargo.toml
index abd5a3a..5a9f4d3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,4 +12,5 @@ clap = { version = "4.4.11", features = ["derive"] }
 chrono = "0.4.31"
 serde = { version = "1.0.193", features = ["derive"] }
 serde_json = "1.0.108"
-colored = "2.1.0"
\ No newline at end of file
+colored = "2.1.0"
+rand = "0.8.5"
diff --git a/src/commands/mod.rs b/src/commands/mod.rs
index 78fdf68..7219386 100644
--- a/src/commands/mod.rs
+++ b/src/commands/mod.rs
@@ -1,2 +1,3 @@
 pub mod init;
-pub mod add;
\ No newline at end of file
+pub mod add;
+pub mod commit;
\ No newline at end of file
diff --git a/src/head.rs b/src/head.rs
new file mode 100644
index 0000000..705fea0
--- /dev/null
+++ b/src/head.rs
@@ -0,0 +1,72 @@
+use crate::utils::util;
+
+pub enum Head {
+    Detached(String),
+    Branch(String),
+}
+
+pub fn current_head() -> Head {
+    let mut head = util::get_storage_path().unwrap();
+    head.push("HEAD");
+    let head_content = std::fs::read_to_string(head).expect("HEAD文件损坏");
+    if head_content.starts_with("ref: refs/heads/") {
+        let branch_name = head_content.trim_start_matches("ref: refs/heads/");
+        Head::Branch(branch_name.to_string())
+    } else {
+        Head::Detached(head_content)
+    }
+}
+
+pub fn update_branch(branch_name: &String, commit_hash: &String) {
+    let mut branch = util::get_storage_path().unwrap();
+    branch.push("refs");
+    branch.push("heads");
+    branch.push(branch_name);
+    std::fs::write(branch, commit_hash).expect("无法写入branch");
+}
+
+pub fn get_branch_head(branch_name: &String) -> std::option::Option<String> {
+    // 返回当前分支的commit hash
+    let mut branch = util::get_storage_path().unwrap();
+    branch.push("refs");
+    branch.push("heads");
+    branch.push(branch_name);
+    if branch.exists() {
+        let commit_hash = std::fs::read_to_string(branch).expect("无法读取branch");
+        Some(commit_hash)
+    } else {
+        None
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::utils::util;
+
+    #[test]
+    fn test_current_head() {
+        util::setup_test_with_mit();
+        let head = super::current_head();
+        assert!(
+            match head {
+                super::Head::Branch(_) => true,
+                _ => false,
+            },
+            "当前不在分支上"
+        );
+    }
+
+    #[test]
+    fn test_edit_branch() {
+        util::setup_test_with_mit();
+        let branch_name = "test_branch".to_string() + &rand::random::<u32>().to_string();
+        let branch_head = super::get_branch_head(&branch_name);
+        assert!(branch_head.is_none());
+
+        let commit_hash = "1234567890".to_string();
+        super::update_branch(&branch_name, &commit_hash);
+        let branch_head = super::get_branch_head(&branch_name);
+        assert!(branch_head.is_some());
+        assert!(branch_head.unwrap() == commit_hash);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index f246b1b..5f577c9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,4 +2,5 @@
 pub mod models;
 pub mod utils;
 pub mod commands;
-mod store;
\ No newline at end of file
+mod store;
+mod head;
\ No newline at end of file
diff --git a/src/utils/util.rs b/src/utils/util.rs
index 6be7ea0..d744e08 100644
--- a/src/utils/util.rs
+++ b/src/utils/util.rs
@@ -5,7 +5,7 @@ use std::{fs, io};
 pub const ROOT_DIR: &str = ".mit";
 pub const TEST_DIR: &str = "mit_test_storage"; // 执行测试的储存库
 
-pub fn setup_test_dir() {
+fn setup_test_dir() {
     let path = std::env::var("CARGO_MANIFEST_DIR").unwrap();
     let mut path = PathBuf::from(path);
     path.push(TEST_DIR);