Pneumatic brake air supply system and control method thereof

Provided is a pneumatic brake air supply system. The system includes an electronic-control air compressor, an engine, an engine control unit, an air compressor electronic-control unit, a pressure sensor and an alarm unit; the electronic-control air compressor is connected with a whole-vehicle air path through an air path after passing through an oil-water separator, a dryer and a four-protection valve successively, the control port of the oil-water separator is connected with the control port of the dryer through an air path, and the engine is electrically connected with the engine control unit; the air compressor electronic-control unit is electrically connected with the engine control unit, the electronic-control air compressor, the pressure sensor and the alarm unit separately, and thepressure sensor is electrically connected with the control port of the oil-water separator and the control port of the dryer separately; when in control, firstly, through the air compressor electronic-control unit, whether or