To overcome the shortage of existing experimental device for partial discharges in gas insulated switchgear(GIS)，an installation for testing PD in GIS with multi-structures is designed, which can simulate T-type，L-type and line-type configurations of GIS expediently. The physical dimension and material parameter are given by calculating the characteristic of the propagation of ultra-high frequency electromagnetic waves and the stress of materials. The experiments under single defect and multiple insulation defects are carried on by using the designed 4 physical models of typical insulated defects for GIS. The results show that the built device can simulate the PD，TE mode and TM mode waves with different wave bands in GIS. The system makes a foundation for the further investigation of the electromagnetic waves propagation，the conditions of generating electromagnetic waves，testing method and pattern recognition of the PD in GIS.