Abstract: To obtain precision degradation model of ball screw mechanism(BSM), an accelerated degradation model of BSM can be established by using the wear characteristics. The accelerated degradation parameter model of BSM can be obtained under different stress levels, through the design of the test device and the friction torque value variation in the test process, and statistical analysis of degradation data was carried out using the method of parameter estimation. At the same time, the positioning reverse variation value of the BSM can be calculated, through different stress conditions of the measured frictional torque of BSM degradation data. The new evaluation method can be provided for BSM positioning precision degradation relied upon the accelerated degradation model. According to the characteristics of BSM wearing very slowly, the accelerated degradation model of BSM can save the test cost and time, and guide the design of the BSM.