diff --git a/vnpy/trader/app/ctaStrategy/ctaGridTrade.py b/vnpy/trader/app/ctaStrategy/ctaGridTrade.py
index 2c09f7a2..1972b7a0 100644
--- a/vnpy/trader/app/ctaStrategy/ctaGridTrade.py
+++ b/vnpy/trader/app/ctaStrategy/ctaGridTrade.py
@@ -1,7 +1,7 @@
 # encoding: UTF-8
 
 
-import os
+import os,sys
 from datetime import datetime
 import json
 import uuid
@@ -298,8 +298,8 @@ class CtaGridTrade(object):
 
         # 状态一致，价格大于最低价格
         if direction == DIRECTION_LONG:
-            if begin == EMPTY_FLOAT: begin = 99999
-            if end == EMPTY_FLOAT: end = -99999
+            if begin == EMPTY_FLOAT: begin = sys.maxint
+            if end == EMPTY_FLOAT: end = 0-sys.maxint
             grids = [x for x in self.dnGrids
                      if x.orderStatus == ordered
                      and x.openStatus == opened
@@ -312,8 +312,8 @@ class CtaGridTrade(object):
 
         # 状态一致，开仓价格小于最高价格
         if direction == DIRECTION_SHORT:
-            if begin == EMPTY_FLOAT: begin = -99999
-            if end == EMPTY_FLOAT: end = 99999
+            if begin == EMPTY_FLOAT: begin = 0-sys.maxint
+            if end == EMPTY_FLOAT: end = sys.maxint
             grids = [x for x in self.upGrids
                      if x.orderStatus == ordered
                      and x.openStatus == opened
@@ -632,10 +632,10 @@ class CtaGridTrade(object):
         """计算网格的平均开仓价"""
         up_open_list = [x for x in self.upGrids if x.openStatus]
 
-        self.max_up_open_price = -99999
-        self.avg_up_open_price = -99999
-        self.min_dn_open_price = 99999
-        self.avg_dn_open_price = 99999
+        self.max_up_open_price = 0 - sys.maxint
+        self.avg_up_open_price = 0 - sys.maxint
+        self.min_dn_open_price = sys.maxint
+        self.avg_dn_open_price = sys.maxint
 
         total_price = EMPTY_FLOAT
         total_volume = EMPTY_INT