Abstract: In order to realize the optimal allocation of resources in electricity market,this paper proposes a decision-making method for transaction optimization in provincial electricity market considering the interaction and cooperation among multiple regions. Firstly,the market transaction structure and mechanism is introduced,taking the maximization of social welfare and trans-regional transacted electricity quantity as clearing objective,in which the social welfare takes into account the transmission and distribution cost of power line. Then multiple constraints such as power grid security constraints,heating unit operation constraints and transaction decision constraints are considered in the optimization decision,and the operation constraints of inter-regional power tie lines are modeled.Finally,the effectiveness of the model is verified by taking Beijing-Tianjin-Tangshan power grid as an example.