The online monitoring of the partial discharge in the high switchgear is an important means of knowing the switchgear health status.8 high frequency pulse current sensor based on the roche coil were installed in the 35 kV switchgear at the waist station,and they were used in online monitoring of the partial discharge.Generally,the partial discharge in the switchgear does not lead to the insulation breakdown,but it can cause the local damage of the dielectric and the strength reducing of the insulation dielectric.