import re
import json
data = (
    """{"Reply":{"Header":{"Method":"mGSSCBetHistory","ErrorCode": "0","MerchantID":"BETSTARtest","MessageID": "H140201152657m6k3f"},"Param":{"TotalRecord":"1","BetDatas":"[{"Column1":""}]","ErrorDesc": ""}}}"""
    )

def escape(match_obj):
    print(match_obj.group(1))
return match_obj.group(1).replace('"', '"')
REGEX = '(?<="BetDatas":")(\\S+)(?=",)'
data = re.sub(REGEX, escape, data)
print(data)
JSON string parsing error in Python