The invention relates to a gravity type biomass feeding device, and belongs to the field of energy chemical equipment. The feeding device comprises a feed bin, a vibrator, an airlock and the like, wherein the airlock is coaxially arranged on the lower part of the feed bin and is driven by a frequency adjustment motor through a speed reducer; the vibrator is arranged on the outer wall on the lower part of the feed bin; the upper part of a feeding pipeline of a reactor is communicated with the lower part of the airlock, and the lower part of the feeding pipeline of the reactor inclines and is communicated with the reactor; blades and a rotating shaft are arranged in the airlock; the blades are arranged on the rotating shaft; and the rotating shaft is in linkage with the frequency adjustment motor by the speed reducer. The feeding device is high in sealing performance, prevents gas in the reactor from leaking into the feed bin on the upper part and prevents external air from entering the reactor, so that the stability of reaction inside the reactor is ensured. According to the feeding device, due to the adoption of a mode of combining mechanical feeding and pneumatic transmission, the flowability of materials in the feeding pipeline of the reactor can be improved effectively, so the materials can be prevented from being agglomerated and blocked in the feeding pipeline of the reactor.