Disclosed is a chemical oxygen self-rescue device, comprising a breathing assembly (1), an oxygen generating assembly (2) and a gas bag (3) sequentially communicated with each other, wherein the oxygen generating assembly comprises an oxygen generating agent tank (21), a gas discharge valve (23) and an oxygen candle (22); the gas discharge valve is arranged on a component above an oxygen generating agent (213) in the oxygen generating agent tank and below a breathing end of the breathing assembly, and the opening and closing of the gas discharge valve are controlled by means of an inflated volume of the gas bag; and a heat radiation assembly and the oxygen generating agent are provided in the oxygen generating agent tank, the heat radiation assembly comprises a vent pipe (211) and a heat radiation frame (212), the vent pipe communicates the breathing assembly with the oxygen generating agent tank, the heat radiation frame is provided in the oxygen generating agent tank, and the oxygen generating agent tank is divided, by the vent pipe and the heat radiation frame, into a plurality of accommodation spaces for the loading of the oxygen generating agent. The chemical oxygen self-rescue device reduces the resistance to breathing, lowers the temperature of breathed gas and improves the utilization rate of the oxygen generating agent.