The invention discloses a high-temperature-resistant self-breakdown gas switch with high reliability. The self-breakdown gas switch is suitable for the occasions with high temperature, high pressure and relatively high reliability requirements. The self-breakdown gas switch mainly comprises a long electrode pole, an electrode, an insulating sleeve, a stainless steel outer cylinder, a connecting gasket and an inflation valve hole, wherein the overall device comprises two parts of a cathode and an anode and is arranged in an axisymmetric manner; the discharge surface of the electrode is an elliptical lead angle; the electrode is welded at one end of the electrode pole through the connecting gasket; and the insulating sleeve tightly sleeves the outside of the long electrode pole and is seamlessly welded with the stainless steel outer cylinder through the connecting gasket. More reliable mechanical strength can be provided when the gas tightness is ensured, so that the condition of structure looseness of the gas switch caused by repeated continuous discharge impact is avoided. The switch can still stably and reliably work in high-temperature and high-pressure environments when the electrical property of the switch is ensured; and the applicability of the gas switch in a special working condition is significantly improved.