For studying the discharge characteristics of fixed metal particles on the basin insulator surface of GIS, a 220kV GIS partial discharge detection platform is taken to simulate discharge model of fixed metal particles on GIS insulator surface, and uses the ultraviolet imaging technology, ultrasonic testing technology and pulse current method are mainly used to detect the whole discharge process. Based on data analysis, the following conclusions can be concluded: 1) Ultraviolet imaging technology is highly sensitive, and the number of UV photons can directly reflect the discharge intensity. 2) The shape of fixed metal particles on the insulator surface have a great impact on discharge intensity. 3) In the basin insulator defects, collisions between charged particle become more intense with discharge intensifing. The collisions result in the increase of sound pressure in macro level, and lead to ultrasonic signal increasing.