diff --git a/src/model/trainer.py b/src/model/trainer.py
index fca8c64..aa6eb05 100644
--- a/src/model/trainer.py
+++ b/src/model/trainer.py
@@ -311,15 +311,22 @@ class Trainer:
 
         return {"eval_loss": avg_loss, "eval_accuracy": accuracy}
 
-    def save_checkpoint(self, filename: str, is_best: bool = False):
+    def save_checkpoint(
+        self, filename: str, is_best: bool = False, is_periodic: bool = False
+    ):
         """
         保存检查点
 
         Args:
             filename: 检查点文件名
             is_best: 是否是最佳模型
+            is_periodic: 是否是定期保存的检查点（会覆盖之前的定期检查点）
         """
-        checkpoint_path = self.checkpoint_dir / filename
+        # 如果是定期保存，使用固定的文件名来覆盖之前的
+        if is_periodic:
+            checkpoint_path = self.checkpoint_dir / "latest_checkpoint.pt"
+        else:
+            checkpoint_path = self.checkpoint_dir / filename
 
         checkpoint = {
             "step": self.current_step,
@@ -506,9 +513,8 @@ class Trainer:
                             # 更新最佳模型
                             if eval_metrics["eval_loss"] < self.best_eval_loss:
                                 self.best_eval_loss = eval_metrics["eval_loss"]
-                                self.save_checkpoint(
-                                    f"step_{global_step + 1}.pt", is_best=True
-                                )
+                                # 只保存best_model，不创建额外的checkpoint文件
+                                self.save_checkpoint("best_model.pt", is_best=True)
 
                         # 记录到TensorBoard
                         self._log_to_tensorboard(log_metrics, global_step)
@@ -535,9 +541,9 @@ class Trainer:
                         accumulated_accuracy = 0.0
                         accumulation_counter = 0
 
-                    # 定期保存检查点
+                    # 定期保存检查点（覆盖之前的定期检查点）
                     if (global_step + 1) % self.save_frequency == 0:
-                        self.save_checkpoint(f"step_{global_step}.pt")
+                        self.save_checkpoint("latest_checkpoint.pt", is_periodic=True)
 
                     # 更新步数
                     global_step += 1