Through the live detection of partial discharge, it is found that there is an insulation discharge phenomenon at the rear lower part of switchgear of 35kV 1 capacitor bank. After power failure inspection, it is confirmed that there are obvious discharge traces, locating at the contact position between A and B phase cabinet terminals. The partial discharge is a serious phenomenon of partial discharge along the surface. Later, through on-site treatment, the power accidents were avoided during the long term operation of the equipment.