GIS (gas insulated switch gear) and GIL (gas insulated line) are important gas insulated transmission equipment in power engineering. Local overheating is one of the typical faults in the GIS and equipment. In order to study the aging and decomposition phenomenon of insulated gas or gas-solid insulation system caused by local overheating defects in GIS / GIL equipment, a local overheating fault simulation test and detection system based on proportional integral differential control is developed in this paper, which realizes automatic measurement and control of local overheating temperature, power measurement and detection of gas decomposition products. The maximum simulated heating power of the system is close to 800W, which is equivalent to the local heating power of the actual equipment. The local high temperature can reach 660 ℃, which meets the requirements of simulating the heating damage of metal conductor parts. The system has good temperature measurement and control ability, the fluctuation value at 400 ℃ is not more than ± 1 ℃, the fluctuation value at 625 ℃ is not more than ± 5 ℃. The fluctuation range of input voltage and current of heating module is not more than ± 1%, and the power consumption is less than ± 1%, the fluctuation range is not more than ± 1.5%. At the same time, through the decomposition tests of C4F7N / CO2 at 625 ℃, gas-solid decomposition involving epoxy resin and SF6 / N2 at 400 ℃, it is verified that the system is suitable for the local overheating fault simulation of pure gas and gas-solid insulation system. Compared with the existing research results, the system has a great improvement in the surface temperature measurement and control of fault components and heating power, and the simulation effect is closer to the actual fault condition of gas insulated equipment.