Abstract: To improve the continuous operation efficiency of inter-provincial medium and long-term electricity markets, a joint clearing model for inter-provincial medium and long-term transactions considering coupling security constraints was designed. Various security constraints were gradually considered in the transaction preparation stage, pre-clearing stage, and joint clearing stage, including generator capacity constraints, transmission channel capacity constraints, provincial transmission node capacity constraints, and electricity balance constraints. In the clearing transaction result stage, to minimize the reduction of electricity consumption, multiple transactions in the same batch that have entered security verification and have spatiotemporal intersections are jointly cleared, efficiently handling the impact of various security constraints, especially coupling security constraints, on transaction results, and improving the enforceability of transaction results. The effectiveness of the joint optimization clearing method is verified through examples. The results show that the joint clearance method can efficiently clear transactions and form transaction results while meeting various safety constraints, which is beneficial for the buyers and sellers to jointly bear the impact of safety constraints and ensure the full utilization of power generation and transmission capacity and the interests of market entities.