The utility model relates to a portable pressure relief ignition device of a sulfur-containing gas well. The device comprises a conversion flange, a square elbow, a plate gate valve, a throttling stopvalve, a flame arrester and a combustion cylinder, wherein the front end of the conversion flange is connected with a gas production tree, the rear end of the conversion flange is connected with a square elbow through an oil pipe, the square elbow is sequentially connected with a plate gate valve, a throttling stop valve, a flame arrester and a combustion cylinder through oil pipes, a gasket, a technical sleeve and a meter sleeve are arranged in the flame arrester, and the meter sleeve is a BX153 steel ring. The conversion flange, the square bend, the plate gate valve and the throttling stopvalve are connected, butt joint installation is facilitated, the pressure relief ignition device is quite suitable for old wells with rugged well site roads, the pressure relief ignition device successfully conducts pressure relief on casing annulus pressure, the problems of long-time well stopping and abandoned well pressure rising are solved, and gas well control safety, simple operation, safetyand reliability are guaranteed.