Space charge effect and partial discharge phenomenon are often used to explain the damage of insulation caused by square wave electric field. Unfortunately, due to the limitations of measurement techniques, it is difficult to analyze the charge transport and its effect on insulation under the such steep rising edge of square waves. Therefore, the influence of characteristic parameters of square wave electric field on charge transport is simulated to provide reference for experimental research. In this paper, the bipolar charge transport model is used to simulate the space charge behavior in polyimide under the square wave electric field with different amplitude, duty ratio and rise time. The increase of amplitude of square wave significantly enhances the accumulation of space charge. As the duty ratio raises, the charge of accumulation first increases followed by a decrease, and the shortening of the rise time causes more serious charge accumulation. The amplitude of electric field is the key factor affecting the charge accumulation on the insulation, but the charge accumulation of the same field intensity under square wave is much smaller than that of the DC. The superposition effect of positive and negative charges is eliminated by simulation. When the polarity of the electric field reverses, there is strong coexistence of positive and negative charges in the insulation, which causes the surge of total charge quantity in the process of rise time. Meanwhile, energy interaction is more obvious in charge transport under periodic electric field, especially in rise time