The implementation of underground distribution lines has grown significantly over the last decades due to the rapid increase of electric energy demand. But, the life of underground lines is determined by strong single or multiple stresses, developed during manufacturing and operation. Establishing and predicting the end of life of a distribution underground line is a task for researchers, designers and manufacturers, too. In this respect, the multiple stress life analysis may be used as efficient tool to predict the life of lines and cables. In this paper, a multiple stress analysis is developed, applying the Arrhenius-Weibull life-stress model, in order to identify the effects of multiple stresses on power cables. An application to an underground power line in a Romanian Electric Network Company is developed, in ALTA software package. The multiple stresses of temperature, humidity, and vibrations are considered, and the life distributions and reliability plots are obtained.