The current electricity transaction process in the electricity market has problems such as high risk, time-consuming, and low efficiency. In order to solve such problems, an improved smart contract electricity transaction model based on blockchain is proposed. The blockchain is a decentralized database with advantages such as non-tampering and encryption security. The blockchain has the advantages of decentralization and high securing. The blockchain and smart contract are applied in the proposed model to improve the efficiency and security of the electricity transaction process. Firstly, the existing problems of the current electricity transaction model are analyzed. Risk assessment is carried out. A decentralized electricity transaction scenario is constructed. Secondly, the reliability coefficient is combined with smart contracts to establish an improved smart contract electricity transaction model based on blockchain. Finally, the feasibility of the model is verified by simulating electricity transaction. The results show that the improved smart contract electricity transaction model proposed is more efficient than the existing transaction model. The model effectively reduces the risk of being attacked and maintain the power market transaction order, thus providing a new idea for the electricity market transaction mode.