Gas insulated switchgear (GIS) is widely used in power grids, the flashover of insulator in GIS is a serious threat to power supply safety. Existing studies have found that metal particles are the main reason for inducing flashover along the surface of insulators, but the development process of partial discharge induced by metal particles is still unclear. Therefore, this paper conducted an experiment on partial discharge induced by metal particles on the surface of insulators based on 126 kV post insulator. The deposition characteristics of space charges induced by partial discharge on the surface of insulators was observed by dust method. The experimental results show that as long as the length of metal particles reaches a certain extent, significant charge will deposited on the surface of insulators. The greater the apparent discharge of partial discharge, the length of the charge deposition area will continue to extend. The area of the charge deposition area is positively correlated with the apparent discharge of partial discharge half-cycle. The space charge deposition on the insulator surface promotes the development of discharge, and the two iterate on each other to form an annular corrugated charge deposition region.