The development of blockchain technology is very rapidly. As a decentralized distributed technology, the blockchain has become one of the most promising Internet applications, and its application in the power balance trading platform has also received extensive attention. In view of the information asymmetry between the trading center and the margin trading users in the power balance trading platform, it is difficult to guarantee the fairness of the transaction and affect the actual income of the production consumers. First, we analyze the trading mechanism of the power surplus market.Then we designed a smart contract for multi-party bidding power resources based on blockchain technology, and achieved the decentralized power trading decision to ensure the information is symmetric and fair.At the same time, the credibility model is established by analyzing the user's recent transaction records, and we design a corresponding punishment mechanism to strengthen the constraint on the execution of offline point-to-point power transactions.