With more internet giants develop online shopping platform, the credit of platform has become the key point of competitive advantages. The sellers are the supplier of credit, while the platform is the supervisor of credit. Game model is built to study the factors affect the seller’s credit supply and the platform’s supervision intensity. We draw suggestions about how to optimize the credit supply, which include proper intensity of supervision, differentiated supervision strategy, improvements of credit evaluation mechanism and supervision of social organizations. Furthermore, the supervision from authentic social organization works more efficiently to the platform with high profits.