In order to improve the reliability and safety of power supply and reduce the failure rate of switchgear, this paper designs a novel high-voltage switchgear which is reliable and safe. A simulation model for electric field and temperature field simulation is established to check the insulation and temperature rise performance of the new designing switchgear. The electric field simulation results show that the place where there has connection or corner has strong chance to occur partial discharge. The heat field results reveal that even in the condition of passing through current with long operation time, the maximum temperature rise of the switchgear is 55.9 K and 48.7 K respectively, which is lower than the standard design requirement 70 K. Some measures can be taken to improve the insulation and temperature rise performance of the new switchgear, such as polishing the connection or using stainless steel at the top of the switchgear.