diff --git a/backend/app/models/schemas.py b/backend/app/models/schemas.py
index 6f191c76..ddc9f922 100644
--- a/backend/app/models/schemas.py
+++ b/backend/app/models/schemas.py
@@ -1,7 +1,7 @@
 """
 Pydantic models for request/response schemas
 """
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 from typing import List, Optional, Dict, Any, Literal, Union
 from datetime import date
 
@@ -9,6 +9,12 @@ from datetime import date
 class AnalysisRequest(BaseModel):
     """Request model for trading analysis"""
     ticker: str = Field(..., description="Stock ticker symbol (e.g., 'NVDA', 'AAPL')", min_length=1, max_length=10)
+    
+    # 防呆：自動將股票代碼轉換為大寫
+    @field_validator('ticker')
+    @classmethod
+    def uppercase_ticker(cls, v: str) -> str:
+        return v.strip().upper()
     analysis_date: str = Field(..., description="Analysis date in YYYY-MM-DD format")
     analysts: Optional[List[str]] = Field(
         default=["market", "social", "news", "fundamentals"],
@@ -140,3 +146,10 @@ class DownloadRequest(BaseModel):
     analysis_date: str = Field(..., description="Analysis date in YYYY-MM-DD format")
     task_id: str = Field(..., description="Task ID of the completed analysis")
     analysts: List[str] = Field(..., description="List of analyst keys to download", min_length=1)
+    
+    # 防呆：自動將股票代碼轉換為大寫
+    @field_validator('ticker')
+    @classmethod
+    def uppercase_ticker(cls, v: str) -> str:
+        return v.strip().upper()
+
diff --git a/cli/main.py b/cli/main.py
index 9e947c12..b322672c 100644
--- a/cli/main.py
+++ b/cli/main.py
@@ -559,7 +559,10 @@ def get_user_selections():
 
 def get_ticker():
     """從使用者輸入中獲取股票代碼。"""
-    return typer.prompt("", default="SPY")
+    ticker = typer.prompt("", default="SPY")
+    # 防呆：將股票代碼轉換為大寫
+    ticker = ticker.strip().upper()
+    return ticker
 
 
 def get_analysis_date():
diff --git a/tradingagents/graph/propagation.py b/tradingagents/graph/propagation.py
index a1cf9430..46a991e7 100644
--- a/tradingagents/graph/propagation.py
+++ b/tradingagents/graph/propagation.py
@@ -41,6 +41,9 @@ class Propagator:
         Returns:
             Dict[str, Any]: 初始狀態的字典。
         """
+        # 防呆：將股票代碼轉換為大寫並去除空白
+        company_name = company_name.strip().upper()
+        
         # 獲取真實公司名稱（從Alpha Vantage獲取公司概況）
         ticker = company_name  # company_name實際上是ticker
         actual_company_name = ticker  # 預設值為ticker
diff --git a/tradingagents/graph/trading_graph.py b/tradingagents/graph/trading_graph.py
index fa473f36..10bc5f4d 100644
--- a/tradingagents/graph/trading_graph.py
+++ b/tradingagents/graph/trading_graph.py
@@ -203,7 +203,9 @@ class TradingAgentsXGraph:
         Returns:
             tuple: 包含最終狀態和處理後信號的元組。
         """
-
+        # 防呆：將股票代碼轉換為大寫並去除空白
+        company_name = company_name.strip().upper()
+        
         self.ticker = company_name
 
         # 初始化狀態