Gas insulated switchgear (GIS) has excellent performances such as small area, not affected by atmosphere, high reliability. So it has been used more and more widely in the power system. However, But the partial discharge (PD) would occur because of insulation defect, PD will lead to the GIS insulation damage after a long time, and will lead to serious consequences without treatment in time, therefore, the PD detection is particularly important. Article simulates the high voltage conductor spikes, basin insulator metal particles on the surface and the shell spike the insulation of the three kinds of typical defects, using the pulse current method and ultrasonic method to test partial discharge signals and get the corresponding signal characteristics, which play a certain guiding significance for field applications.