The invention discloses a biomass feeding system. The biomass feeding system includes a hopper lifting system, a stock bin system, a sealing system and a feeding system, wherein the hopper lifting system includes a material bin, an electric motor, a reducer, a hopper and a traction belt; the stock bin system comprises an upper stock bin, a middle stock bin and a lower stock bin; the sealing systemincludes an upper sealing valve, a lower sealing valve, a double-acting hydraulic cylinder, a hydraulic oil tank and a hydraulic pump; and the feeding system includes an electric motor, a reducer anda screw conveyor. The biomass feeding system adopts a mutual independent design of the hopper lifting feeding system, the stock bin and the sealing system, and adopts a combination structure of the three-stage stock bin including the upper stock bin, the middle stock bin and the lower stock bin and the dual-stage sealing system, so that the gas in a high-pressure gasification chamber can be effectively prevented from reversely moving to the stock bin in the process of biomass gasification and the pressure stability of the high-pressure gasification chamber can be ensured.