The invention discloses a discharging system of a fluidized bed reactor and a method thereof. The system comprises a settlement container and a transfer container, an injector is arranged between the settlement container and the fluidized bed reactor, a pipeline of an inlet at the bottom is connected with an outlet at the top of the fluidized bed reactor, a pipeline a separated from the pipeline is connected with the inlet of the injector; a pipeline d at the upper part of the settlement container is connected with the bottom of the injector; the outlet of the injector is connected with the lower part of the fluidized bed reactor; a discharge pipeline b at the upper part of the fluidized bed reactor is connected with the top of the settlement container; a balance pipeline e is arranged between the top of the settlement container and the top of a transfer container; a main inlet valve is arranged on the pipeline a, a main drain valve A is arranged on the discharge pipeline b, a transfer valve is arranged on the pipeline d, and a main balance valve is arranged on the pipeline e. The discharging system of the fluidized bed reactor can obviously increase the discharging efficiency of a pressure vessel of a fluidized bed during a condensation state technology. Liquid content of the discharged materials is reduced, the burden of a degassing cabin is reduced, and energy consumption is reduced.