Abstract: In order to obtain the equivalence of accelerated aging test of insulating paper under the synergistic effect of cyclic stress and temperature, the steady-state strain of insulating paper was derived based on the three-variable model of insulating paper. At First, based on the time-temperature- stress equivalence principle, combined with free volume theory, a modified time-temperature-stress equivalence theory considering the stress frequency was obtained. Secondly, a series of accelerated mechanical-thermal aging experiments were carried out at 130℃ with 4 different stress levels and three different stress frequencies, and the influence of stress level and frequency on the tensile strength loss rate model of insulating paper was obtained. Then, the stress-time shift factor was defined, and the master curve of tensile strength loss rate of insulating paper was obtained, and a novel method to establish the shift factor was proposed. The conclusion of this paper verifies the equivalence of accelerated aging test and thermal aging test of insulating paper from both theoretical and experimental aspects, which can provide theoretical support for accelerated aging test and life evaluation of insulating paper.