A common method for measuring discharge capacitance is Lissajous figure method，which required precise the slopes of adjacent sides of the Lissajious figure．Since Lissajious figures are not always regular parallelograms，It is difficult to determine the slopes of adjacent sides．A new capacitance probability histogram method is proposed to calculate the volume discharge load capacitance of the electrode gap． Using the capacitance probability histogram method to calculate the volume discharge load capacitance are as follows: (1)perform nonlinear interpolation on the actually collected data to ensure that the voltage data has the same data points in each full cycle;(2)Savitzky-Golay smoothing is performed on the interpolated voltage data，and the appropriate smoothing window points (200)and polynomial order (2)should be selected during smoothing;(3)choose the right screening interval and the statistical period． The reliability of measuring discharge capacitance by this method is verified．