Aimed at the crack problem in the tungsten carbide (WC) coating on the friction pair of the hydraulic cylinder,a key component of the control rod hydraulic drive mechanism for nuclear reactor,the research on grinding process optimization and stress relief treatment of WC coating was carried out.The basic properties and friction and wear performance of the WC coating prepared by the optimized process,and the cold state performance of hydraulic cylinder were tested.The results show that the improved preparation process solves the crack problem of WC coating.The basic performance and friction and wear performance,the cold state motion resistance,and leakage rate of the hydraulic cylinder coating processed by this process can meet the operating requirements of the control rod water pressure drive mechanism.The research results lay a foundation for the overall performance research of the control rod hydraulic drive mechanism,as well as the further development and engineering application of the control rod hydraulic drive technology.