diff --git a/src/services/claudeRelayService.js b/src/services/claudeRelayService.js
index dab6824a..ddf75f4e 100644
--- a/src/services/claudeRelayService.js
+++ b/src/services/claudeRelayService.js
@@ -789,7 +789,8 @@ class ClaudeRelayService {
       return total
     }
 
-    const removeFromMessages = () => {
+    // 只移除 cache_control 属性，保留内容本身，避免丢失用户消息
+    const removeCacheControlFromMessages = () => {
       if (!Array.isArray(body.messages)) {
         return false
       }
@@ -803,12 +804,8 @@ class ClaudeRelayService {
         for (let contentIndex = 0; contentIndex < message.content.length; contentIndex += 1) {
           const contentItem = message.content[contentIndex]
           if (contentItem && contentItem.cache_control) {
-            message.content.splice(contentIndex, 1)
-
-            if (message.content.length === 0) {
-              body.messages.splice(messageIndex, 1)
-            }
-
+            // 只删除 cache_control 属性，保留内容
+            delete contentItem.cache_control
             return true
           }
         }
@@ -817,7 +814,8 @@ class ClaudeRelayService {
       return false
     }
 
-    const removeFromSystem = () => {
+    // 只移除 cache_control 属性，保留 system 内容
+    const removeCacheControlFromSystem = () => {
       if (!Array.isArray(body.system)) {
         return false
       }
@@ -825,12 +823,8 @@ class ClaudeRelayService {
       for (let index = 0; index < body.system.length; index += 1) {
         const systemItem = body.system[index]
         if (systemItem && systemItem.cache_control) {
-          body.system.splice(index, 1)
-
-          if (body.system.length === 0) {
-            delete body.system
-          }
-
+          // 只删除 cache_control 属性，保留内容
+          delete systemItem.cache_control
           return true
         }
       }
@@ -841,12 +835,13 @@ class ClaudeRelayService {
     let total = countCacheControlBlocks()
 
     while (total > MAX_CACHE_CONTROL_BLOCKS) {
-      if (removeFromMessages()) {
+      // 优先从 messages 中移除 cache_control，再从 system 中移除
+      if (removeCacheControlFromMessages()) {
         total -= 1
         continue
       }
 
-      if (removeFromSystem()) {
+      if (removeCacheControlFromSystem()) {
         total -= 1
         continue
       }