Abstract: In order to verify accuracy of values of grounding insulation resistance and distributed capacitance of underground low-voltage power grid measured by AC voltammetry and AC-DC voltammetry, the paper introduced theory analysis and deduction of calculating formula of the two methods, and made comparison for measuring results of the two methods by use of analog circuit of underground low-voltage power grid. It got conclusion that the error of values of grounding insulation resistance and distributed capacitance measured by AC-DC voltammetry is smaller.