Having studied harmonic’s impact on electronic integrator’s Calibration. The mathematics model of the integrator and the response of the integrator simulator to volt-second pulse periodic signal have been established through SIMUNLINK in the MATLAB, it theoretically analyzes the low-pass filtering characteristics of ideal integrators and the impact of pulse signal harmonics on approximate integrators. The experiment shows that the bigger the harmonics elements in the volt-second’s pulse signal is, the less accurate its calibration of integrator will be.