The invention relates to a method for the GIS on-site impulse withstand voltage test. The method is characterized by comprising the following steps: 1) obtaining the equivalent parameter of each interval of a tested GIS, and constructing a GIS distribution parameter model; 2) according to the distribution parameter model, carrying out the distribution calculation of the impulse voltage in the GIS;3) calculating the impulse voltage parameters of each interval of the GIS; 4) determining the number of segments according to the parameters; 5) performing the segmented impulse withstand voltage test on the GIS according to the number of segments. The test method disclosed by the invention is adopted and then the waveform parameters of the overvoltage of each interval of the tested GIS can be determined through overvoltage calculation. As a result, the number of segments is determined according to the waveform parameters. The test efficiency and the realization effect are guaranteed.