The invention discloses a method for charging and discharging air as well as maintaining and controlling air pressure. The method comprises the steps of inputting the needed target air pressure value Paim into an electronic control unit (ECU) control system by an enable keyboard; subtracting the Paim and current air pressure value Pe of a target air chamber to obtain difference, and comparing the obtained difference with the air pressure dead zone value Pd; if the difference of Paim and Pe is larger than Pd, controlling an air charging electromagnetic valve to charge air by the ECU control system which generates the corresponding pulse signal according to the duty ratio; if the difference of Paim and Pe is less than Pd, controlling an air discharging electromagnetic valve to discharge air by the ECU control system according to the duty ratio; when the absolute value of the difference of the target air pressure value Paim and the current air pressure value Pe is less than the air pressure dead zone value Pd, controlling the electromagnetic valves to stop working by the ECU control system according to the duty ratio at the moment. After the method is adopted, air charging and discharging can be carried out on the closed air chamber with any form; when the air chamber with the unknown pressure value reaches the needed air pressure value after being manually adjusted, the air chamber can be switched into an automatic control mode at any time, and the current air pressure value is maintained to be constant; the method is simple in operation and high in controllable degree.