The hydraulic lock phenomena happened in the clearance of multi-way valve is one of the common faults of the hydraulic control system of engineering machinery.In order to reduce the lock force and improve the accuracy and reliability of direction switching of the multi-way valve,the mathematical model based on average flow Reynolds equation and the contact model of rough surface of the valve were set up,and the finite volume method was used to obtain its numerical discretization.The effect of numbers of pressure-equalizing grooves on radial lock force of the valve and the effect of surface roughness of valve on inner leakage rate and friction were discussed.The simulated results show that the radial lock force of the valve can be reduced by increasing the numbers of pressure-equalizing grooves.With the increasing of surface roughness of the valve,inner leakage and viscous force are reduced,but the friction of rough peak is obviously increased.