While the demand of electric power increases and the installation space of power equipment is fixed in a factory, the gas insulated switchgear (GIS) is gradually applied to medium voltage system due to its small size and easy maintenance. However, it also takes longer time for the repair of GIS accident. Therefore, the preventive maintenance (PDM) is very important and the most effective method is partial discharge measurement. Unfortunately, the metal-cladded GIS usually makes PDM inconvenient, especially for the partial discharge location. This paper provides a fast and easy method for the location of partial discharge in GIS, it can locate the defect quickly and effectively, and the related strategy can be made in advance.