The invention discloses a fiber screening machine rapid brake apparatus and method. The apparatus comprises a pneumatic brake, a solenoid valve, a compression air source, a pressure controller, a PLC, a speed detection device and an inertia detection device, wherein the air inlet of the pressure controller is connected with the air outlet of the solenoid valve, the air outlet of the pressure controller is connected with the air inlet end of the pneumatic brake, and the solenoid valve is installed on a pipeline of an outlet of the compression air source; and the speed detection device is used for detecting a speed of a line laying main shaft, the inertia detection device is used for detecting inertia of the line laying main shaft, the speed detection device and the inertia detection device are both connected with the input end of the PLC, and the output end of the PLC is connected with the solenoid valve and the pressure controller. According to the method, the acting frequency of the solenoid valve is controlled according to the operation speed of the line laying main shaft, and output pressure of the pressure controller is controlled according to the moment of inertia of the line laying main shaft during a brake, such that a rapid and stable brake effect can be realized, at the same time, equipment loss can also be reduced.