Extensive interest has been focused on aging phenomena of polymeric power cables. Aging of polymeric power cables is a significant subject of investigation during the last few decades. Despite the great achievements in aging mechanisms by single aging stress, much less is known about the aging phenomena and related aging mechanisms of cables under multi-stress aging conditions. The accelerated electrical aging of 15 kV Ethylene Propylene Rubber (EPR) power cables under multi-stress conditions was conducted. The test conditions and results were summarized in this paper. The experiment aims at obtaining a comprehensive understanding of the accelerated aging phenomena of EPR cable insulation and the impacts from different aging factors. The study also fulfills the need to assess the long-term reliability of the EPR cables used in the similar environment.