Abstract: To establish the standard high impulse voltage measurement system, low impedance impulse voltage calibrator with high accuracy and stability is developed and studied since it can be used as a primary reference of impulse voltage measurement. The values and uncertainties of the output waveform parameters could be calculated according to the values and corresponding uncertainties of the circuit elements. In this paper, a 1 kV low impedance impulse voltage calibrator with the theoretical time parameters of 1.56ms/60ms, was developed and its schematic diagram was analyzed. The evaluation process of the value and uncertainties of waveform parameters based on the Random Fuzzy Variable method was detailed presented. The calibrator was measured and its experimental performance was tested. The result show that the evaluated uncertainties are quite accordance with those evaluated by traditional method which verified the applicability of Random Fuzzy Variable method when evaluating the calibrator.