The invention discloses a confined space fire and suffocation prevention device and method. The device comprises an air extraction system, a smoke detector, an oxygen sensor and a controller. The smoke detector is used for detecting the smoke concentration in a confined space. The oxygen sensor is used for detecting the oxygen concentration in the confined space. The air extraction system is usedfor extracting air. The controller is connected with the smoke detector, the oxygen sensor and the air extraction system and controls the air extraction system. The method includes the steps that thesmoke concentration and the oxygen concentration in the confined space are detected in real time; whether the smoke concentration in the confined space is larger than or equal to a first preset valueor not is judged; if the smoke concentration in the confined space is larger than or equal to the first preset value, gas in the confined space is extracted outside the confined space; whether the oxygen concentration in the confined space is smaller than or equal to a second preset value or not is judged; and if the oxygen concentration in the confined space is smaller than or equal to the secondpreset value, gas outside the confined space is extracted into the confined space. No pollution can be generated in the fire extinguishing mode, and the safety of an infant can be improved in the oxygen supply mode. The device and method has the beneficial effects that fire is extinguished without pollution, and oxygen is supplied without potential safety hazards.