Abstract: This paper explores the design and test of the high temperature and high pressure water medium bearing test bench system, and mainly introduces the multi-modular design and linkage function of the test bench system and the configuration of each system. Taking the control rod drive mechanism bearing in the nuclear reactor as the test object, the test platform is used to simulate the high-temperature and high-pressure conditions of 300 ℃ and 15 MPa, and the 40 h long life performance test of the water medium bearing is carried out. Through the long-term assessment of the bearing performance and durability life, monitoring the speed, torque, temperature, pressure and other parameters in the test process, it is verified that the reliability and stability of the test platform meet the design requirements. It provides reliable support and reference for the design and stability of domestically produced high-temperature and high-pressure bearings on the high-temperature and high-pressure bearing test bench.