diff --git a/astrbot/core/config/astrbot_config.py b/astrbot/core/config/astrbot_config.py
index c42088ba9e..b7da0ff431 100644
--- a/astrbot/core/config/astrbot_config.py
+++ b/astrbot/core/config/astrbot_config.py
@@ -2,6 +2,7 @@
 import json
 import logging
 import os
+import tempfile
 
 from astrbot.core.utils.astrbot_path import get_astrbot_data_path
 from astrbot.core.utils.auth_password import (
@@ -53,9 +54,9 @@ def __init__(
 
         if not self.check_exist():
             """不存在时载入默认配置"""
-            with open(config_path, "w", encoding="utf-8-sig") as f:
-                json.dump(default_config, f, indent=4, ensure_ascii=False)
-                object.__setattr__(self, "first_deploy", True)  # 标记第一次部署
+            self.update(default_config)
+            self.save_config(indent=4)
+            object.__setattr__(self, "first_deploy", True)  # 标记第一次部署
 
         with open(config_path, encoding="utf-8-sig") as f:
             conf_str = f.read()
@@ -211,15 +212,33 @@ def check_config_integrity(self, refer_conf: dict, conf: dict, path=""):
 
         return has_new
 
-    def save_config(self, replace_config: dict | None = None) -> None:
+    def save_config(
+        self, replace_config: dict | None = None, *, indent: int = 2
+    ) -> None:
         """将配置写入文件
 
         如果传入 replace_config，则将配置替换为 replace_config
         """
         if replace_config:
             self.update(replace_config)
-        with open(self.config_path, "w", encoding="utf-8-sig") as f:
-            json.dump(self, f, indent=2, ensure_ascii=False)
+        directory = os.path.dirname(os.path.abspath(self.config_path)) or "."
+        fd, temp_path = tempfile.mkstemp(
+            dir=directory,
+            prefix=f".{os.path.basename(self.config_path)}.",
+            suffix=".tmp",
+        )
+        try:
+            with os.fdopen(fd, "w", encoding="utf-8-sig") as f:
+                json.dump(self, f, indent=indent, ensure_ascii=False)
+                f.flush()
+                os.fsync(f.fileno())
+            os.replace(temp_path, self.config_path)
+        except Exception:
+            try:
+                os.unlink(temp_path)
+            except FileNotFoundError:
+                pass
+            raise
 
     def __getattr__(self, item):
         try:
diff --git a/tests/unit/test_config.py b/tests/unit/test_config.py
index 7afe82ebed..d6747930d2 100644
--- a/tests/unit/test_config.py
+++ b/tests/unit/test_config.py
@@ -529,6 +529,38 @@ def test_save_config_with_replace(self, temp_config_path, minimal_default_config
         # Original fields are preserved because update merges
         assert "platform_settings" in loaded_config
 
+    def test_save_config_preserves_existing_file_when_write_fails(
+        self, temp_config_path, minimal_default_config, monkeypatch
+    ):
+        """Config saves should not corrupt the existing file on write failure."""
+        config = AstrBotConfig(
+            config_path=temp_config_path, default_config=minimal_default_config
+        )
+        with open(temp_config_path, encoding="utf-8-sig") as f:
+            original_content = f.read()
+
+        def failing_dump(*args, **kwargs):
+            file_obj = args[1]
+            file_obj.write("{")
+            raise RuntimeError("simulated interrupted write")
+
+        config.new_field = "new_value"
+        monkeypatch.setattr(
+            "astrbot.core.config.astrbot_config.json.dump",
+            failing_dump,
+        )
+
+        with pytest.raises(RuntimeError, match="simulated interrupted write"):
+            config.save_config()
+
+        with open(temp_config_path, encoding="utf-8-sig") as f:
+            assert f.read() == original_content
+        assert [
+            entry.name
+            for entry in os.scandir(os.path.dirname(temp_config_path))
+            if entry.name != os.path.basename(temp_config_path)
+        ] == []
+
     def test_modification_persists_after_reload(
         self, temp_config_path, minimal_default_config
     ):