The invention discloses a method and a device for air-floatation flow-state high-temperature heat-transfer gasification of biomass. The method comprises the following steps: (1) stirring a biomass gasifying raw material so as to form a mist state; (2) cracking under the heating of high temperature smoke at 800-1000 DEG C so as to obtain high temperature tar gas; (3) carrying out high temperature cracking and gasification on the high temperature tar gas and steam at the temperature of 1050-1150 DEG C; and (4) filtering, condensing and purifying solid residue and gas while stirring so as to obtain gas with a middle heat value. The device comprises a gas making furnace and at least one coke cracking furnace, wherein the gas making furnace comprises a gas collecting chamber and a stirring chamber; and the coke cracking furnace comprises an upper coke cracking furnace gas collecting chamber provided with a coke cracking furnace row tube, and a coke cracking furnace row tube shell layer is communicated with a gas making furnace row tube shell layer. According to the invention, a heat source in the whole cracking and gasification process is derived from high temperature smoke generated by combustion of a biomass micrometer fuel which is a renewable clean energy and is wide in source and low in cost. The method and device provided by the invention have the characteristics of high heatefficiency, high gas making efficiency and high gas heat value.