The non-equilibrium body tube pitch system is a typical electro-hydraulic servo system.Achieving high-precision position control under road roughness conditions can effectively improve the long-range accuracy of gun weapons.Therefore,the working principle of the non-equilibrium body tube pitch system and the mechanism of road roughness influence were analyzed.The mathematical models of each component were established and the system state space model was obtained.Furthermore,based on the quasi-sliding mode,a double power reaching law sliding mode controller with improved saturation function was designed.Finally,a simulation model of the non-equilibrium body tube pitch sliding mode control under road roughness conditions was built.The simulation analysis was performed and compared with the control effect of sliding mode controllers with exponential reaching law and double power reaching law to verify the feasibility and effectiveness of the proposed method.The results show that the proposed method has the advantages of high tracking accuracy,short response time,good chattering reduction effect,and low energy consumption,which can meet the requirements of high-precision control of dynamic non-equilibrium body tube.