The main steering rudder surface of civil aircraft usually adopts the design of redundant degree actuator channels to meet the requirements of high safety of flight control systems. However, the use of the main-main actuator operating leads to a force fight phenomenon, which can bring fatigue and other effects on the rudder surface structure and even threaten flight safety. In this paper, the rudder operating system with three residual degrees of main-main-main operation is taken as the object. A proportional-integral equalization algorithm based on the dual compensation of actuator pressure difference and position is investigated to mitigate the force fight phenomenon. The effectiveness of this force fight equalization method is verified by Simulink simulation and the iron bird experiment.