Abstract: The study on the self-breakdown characteristics of air-insulated gas switches at different environmental temperatures can improve the adaptability of pulsed power devices, especially in the fields of shale oil and gas resource exploitation. By establishing a research platform for the high-temperature performance study of coaxial gas switches, the self-breakdown voltage distribution of gas switches at different temperatures was experimentally studied. The main factors and laws of temperature on the self-breakdown discharge process were analyzed in combination with Townsend discharge theory. The results show that, the main factors affecting the self-breakdown voltage are the density of the air and the distance of the switch at different temperatures. For cavity-exchangeable gas switches, the self-breakdown voltage decreases with the increase of temperature. However, with the increase of environmental temperature, the high-temperature particles sprayed during the ablation process of the electrode cause molecular pyrolysis and gas adsorption on the surface of the insulating material, as well as the chemical reaction of gas molecules in the process of high-current discharge, resulting in obvious changes in the composition of the gas and the reduction of the stability of the switch discharge. The research results in this paper can provide a technical reference for the reliable operation of gas switches in high-temperature environments.