The force fighting in the parallel actuation system twists the main bearing structure of the airplane main control surface,reduces the fatigue life of the surface,and even breaks the surface,which affects the flight safety.Taking the parallel mechanical hydraulic actuation system as the research object,its physical structure was deeply analyzed,the simulation model of system force fighting was established,the single influencing factors and the combination influencing factors on system force fighting were studied,the main influencing factors of system force fighting were find out,and the relevant methods to mitigating force fighting were put forward.The research results show that the flow gain of the main control valve and the cover of the valve port have great impact on the force fighting of the parallel mechanical hydraulic actuation system.Under the combination of sensitive factors,it is feasible to reduce the force fighting through the design,selection and adaptation of the main control valve.