Abstract: The solid thermal storage system needs to connect the 66 kV power to a device with an internal and external temperature difference of nearly 500℃ through a wall bushing. As a key component for external connection, the insulation characteristics of high temperature and high voltage wall bushings are particularly important for the safety of equipment operation. In order to meet this special situation, the design of the through-wall bushing structure was improved, and an electric heating coupling model was established. The insulation characteristics of the quartz glass wall bushing with SF6 gas as a heat dissipation medium were carried out under the complex conditions of 66 kV and 300～800℃ simulation analysis. The results show that the weakening of the insulation strength of the wall bushing in the high temperature and high voltage environment is mainly at the end of the bushing, which can be improved by adjusting the thickness of the vacuum layer. At the same time, the experiment of heating and pressing test proves that high temperature and high voltage wall bushing can achieve insulation under high temperature and high voltage.