diff --git a/apps/api/src/services/chat_manager.py b/apps/api/src/services/chat_manager.py
index 37a8f298..7ab341f0 100644
--- a/apps/api/src/services/chat_manager.py
+++ b/apps/api/src/services/chat_manager.py
@@ -105,8 +105,8 @@ class ChatManager:
             logger.warning("openclaw_gemini_monthly_limit_reached", current_usd=current_cost, limit_usd=MONTHLY_LIMIT_USD)
             return f"🔴 OpenClaw 本月 Gemini 用量已達上限 ${MONTHLY_LIMIT_USD} USD（已用 ${current_cost:.4f}）"
 
-        # Gemini 2.0 Flash: 快速、便宜 (與 models.json 對齊)
-        model = "gemini-2.0-flash"
+        # Gemini 2.0 Flash-Lite: 最便宜 (2026-04-03 老闆指示)
+        model = "gemini-2.0-flash-lite"
         try:
             async with httpx.AsyncClient(timeout=30.0) as client:
                 resp = await client.post(
@@ -125,8 +125,8 @@ class ChatManager:
                 usage = data.get("usageMetadata", {})
                 in_tok = usage.get("promptTokenCount", 0)
                 out_tok = usage.get("candidatesTokenCount", 0)
-                # Gemini 2.0 Flash: Input $0.10/1M, Output $0.40/1M
-                cost = (in_tok * 0.0000001) + (out_tok * 0.0000004)
+                # Gemini 2.0 Flash-Lite: Input $0.075/1M, Output $0.30/1M
+                cost = (in_tok * 0.000000075) + (out_tok * 0.0000003)
                 new_total = current_cost + cost
 
                 try: