Switchgear is widely used in transmission and distribution networks, and its operation status is directly related to the reliability and safety of power supply. This paper takes the 35 kV switchgear as the research object and explores its insulation characteristics. Firstly, the partial discharge simulation calculation of the switchgear is analyzed and the electric field calculation model of the switchgear is established; secondly, different kinds of local discharge faults are set up in the model to investigate the influence on the insulation strength of the switchgear; finally, the insulation performance of the switchgear specimen is characterized by four parameters, namely, partial discharge, change of insulation resistance, relative permittivity and current leakage through the setup of the simulation experiment. The results of the experiment proved that the above four parameters have been analyzed by the simulation experiment. The experimental results prove that the above four parameters can effectively respond to the real-time operation of the switchgear insulation and prevent the switchgear from insulation degradation or failure. The research in this paper provides certain data support for the optimization strategy of switchgear insulation performance.