Abstract: This paper described the single stress & multi-stress level module of the accelerated life test design and evaluation software ALT511. The module included four tabs: data import, life distributions under each stress level, acceleration model fitting, and reliable life value under specified stress level. Detailed introductions of the exponential and Weibull distribution fitting methods based on multi-stress level failure data, the acceleration model fitting methods based on Arrhenius and inverse power law, as well as the calculation methods for reliable life, failure probability density function and reliability function with and without confidence under a specified stress level were proposed. Finally, a software application case was presented for the accelerated life test of a spacecraft ultrasonic motor. The fitting results of the acceleration model are consistent with those given by Microsoft Excel, and the calculation results of reliable life are almost identical with those given by Minitab. The software ALT511 may provide a reference and support for the design and application of accelerated life test software in China.