Abstract: During the design, manufacture, installation, operation and maintenance of gas insulated metal enclosed switchgear (GIS), metal foreign matters would be produced, which would lead to partial discharge and even arc discharge in the interior. Through the establishment of foreign matter comparative analysis database, the composition data of GIS related known materials and discharge foreign matters were formed into a systematic and perfect database. In the analysis of discharge foreign matter, through the comparative analysis of the composition data of discharge foreign matter and the composition of known materials in the established database, the material and source of discharge foreign matter could be quickly and accurately obtained. This method could provide reliable data support for the investigation and research of the field discharge accidents of GIS manufacturers and users, and also provide a theoretical basis for how to prevent the remixing of discharge foreign matters in the process of GIS assembly, test and installation.