Abstract: To complete the life evaluation of ball screw in a short time, a model of accelerated life testing was established through the way of strengthening load, and an accelerated life test design and reliability analysis method with single sample, double-stress and three levels was proposed. The virtual augmented method was used to extend the failure time data under three step acceleration double stresses equivalently for improving the accuracy of reliability evaluation of ball screw in the case of single sample and less data. Then, the parameters of Weibull distribution model under three step accelerated double stress levels were estimated by least square method. Finally, the life of the ball screw under normal stress level was calculated according to the acceleration equation, and the reliability life index of the ball screw was determined. The feasibility of evaluating the reliability of ball screw using double-stress accelerated life test without changing the failure mechanism was verified by simulations, which can improve the efficiency of ball screw life assessment.