To research the influence of quasi-DC transversal electrical discharge plasma on the fuel jet flowfield in the combustor of scramjet under the pulse control, the pulse quasi-DC transversal electrical discharge plasma model was established. Under different pulse excitation frequency, taking advantages of numerical simulation, the influence of plasma on the formation feature of cavity fuel jet flowfield, loss of combustor total pressure, the mixing efficiency of the jet downstream was analyzed. The results show that, under pulse plasma condition, the position and intensity of the upstream separation shock can be controlled effectively, the periodic fluctuation of the cavity flowfield due to the pulse control, which improved the mixing efficiency of the fuel and mainstream, can decrease the total combustor pressure losses contrast to steady control.