In order to make track objective current of analog load real-time for the AC electronic load, referring to the working conditions of Delta convertor, the advantages and disadvantages of hysteresis control and triangular wave control methods are derived by analyzing the work characteristics: the triangular control has constant frequency, and tracking error is less than the amplitude of the triangular wave. The amplifier gain is limited, the average value in switching period of current error is not zero, and the output signal has less harmonic content, containing the triangle frequency and its double frequency harmonic in low frequency. When the current error slope is higher than the triangular wave slope, the comparator can appear multiple intersecting comparison point, resulting in a high switching frequency. Hysteresis current control response fast, but has rich harmonics, which is not conducive to the filter. Based on the derived function relationship between the width and the switching frequency, a kind of fixed switching frequency hysteresis control method is obtained, and the superiority of the control is verified by simulation experiment.