Protection types of equipment are the mainstay of a power system. Recently, gas insulated metal-enclosed switch-gear (GIS) has developed the most important part of a power system protection. High-pressure gas insulated metal-enclosed switchgear may suffer overheating and can cause fatal accidents. The miniaturization and high performance of electrical equipment highlight the importance of thermal analysis. In this paper, the model simplification method of gas insulated metal-enclosed switchgear is studied and the complex structure of GIS is simplified according to the heat source of GIS. The heat source of GIS includes Joule heat of conductor and contact resistance heating. Furthermore, this paper considers the cooling effect of natural convection SF6. By employing the method of AC electromagnetic analysis and fluid-solid coupling analysis, harmonics under the effect of eddy current losses and the contact resistance method for the convection heat dissipation (for shell and air) have been selected. Finally, obtain the temperature distribution of gas insulated metal-enclosed switchgear. The simulation results are verified by temperature rise test. Thermal simulation analysis of gas insulated metal-enclosed switchgear is carried out, which can provide a theoretical and experimental reference for further research and design of improved protected products.