The invention provides a motor train unit rapid air exhaust system which comprises a first air cylinder, a second air cylinder and a third air cylinder. The first air cylinder is connected with a detachable pressure gauge in a carriage through a first pipeline; a commonly-used brake controller and a first valve are arranged on the first pipeline; the second air cylinder is connected with a brake pipeline through a pipeline set; and the pipeline set comprises a third valve, a handle, an emergency brake button and a standby brake controller which are located in a driver room. According to the air exhaust system, the air exhaust operation space is large, danger of operators in the operation process is reduced, and safety of operation is improved. The invention further provides a motor train unit rapid air exhaust method. The method comprises the steps that the emergency brake button is pressed down, and the pressure gauge is dismounted to open a first air exhaust channel, and air exhaust is conducted; and a second valve and the third valve are opened, and the handle is pushed to the front gear to open a second air exhaust channel, and air exhaust is conducted. The air exhaust method improves the working efficiency.