In view of the long life and slow degradation of RV reducers used in industrial robots, a method is proposed to evaluate the reliability of RV reducers based on the high stress accelerated degradation test and the modeling of transmission accuracy degradation. The maximum loading value of the accelerated test is determined by strength verification of the weak links. To obtain the degradation amount of the RV reducer transmission accuracy, the accelerated degradation test is conducted on three RV reducers under this loading value. According to the degradation characteristics of the RV reducer transmission accuracy, the degradation trajectory of the transmission accuracy of each reducer is modeled by using the maximum likelihood estimation method with sample data separation. The initial performance degradation and drift coefficient in the Wiener degradation model are set as constant values, and the coefficient of variation of the diffusion coefficient is obtained, assuming that the diffusion coefficient obeys normal distribution to find the reliability of the RV reducer. The results show that the high stress accelerated degradation test can provide reliable test data for RV reducer reliability analysis and save test costs. The proposed method can realize the reliability analysis of RV reducer under small sample conditions while reflecting individual differences, and can accurately calculate the failure probability of RV reducer, which is important for improving the working performance of industrial robots.