With the construction of the unified power market system, the integrated development of regional power markets has gradually accelerated, and the scale of the electricity trade across provinces and regions has been continuously expanded. A transmission income distribution method for multiple transmission network operators in regional integrated market based on the existing transmission and distribution price verification and charging mechanism is proposed. The transmission paths of electricity trade contracts across provinces and regions are optimized with the minimum network loss as the objective function, and the fixed transmission income is allocated according to the utilization of transmission network operator assets. Through the rational distribution of transmission income, the electricity trade scale of the regional market is expanded, which promotes the optimal allocation of transmission resources in the regional market. Finally, the effectiveness of the method is verified by an example of IEEE-30 node system.