The air respirator is a self-contained open respirator with positive pressure of compressed air. The staff exhales gas from the lungs through the full face mask, and the breathing valve is discharged into the atmosphere. When the staff exhales, an appropriate amount of fresh air is opened and closed by the gas storage cylinder, and the flexible conduit supply valve in the pressure reducer. The full face mask inhales the gas into the human lungs, completing the whole respiratory cycle, In this process of breathing and circulation, since there are two suction valves and exhalation valves in the full mask, which are opened in one direction during the breathing process, the whole airflow direction is always moving in one direction, forming the whole process of breathing and circulation. Open the cylinder valve, and the high-pressure air flows through the cylinder valve and pressure reducer in turn. After the primary decompression, the medium pressure gas of about 0.7MPa is output, and then it is sent to the air supply valve through the medium pressure air duct. The air supply valve depressurizes the medium pressure gas according to the wearer's suction capacity. The depressurized gas enters the mask for the wearer to breathe. The turbid gas exhaled by the human body is discharged into the atmosphere through the exhalation valve on the mask, In this way, the gas always flows in one direction without going against the current.