The invention discloses a method used for producing bio-oil by utilizing biomass, and a pyrolyzing device; wherein, the method comprises the steps as follows: the biomass is pyrolyzed under anoxic condition to generate solid coke and gas; the coke is intercepted to form a coke layer and moves out of a furnace body, and during the period, the coke generates cracking reaction further and liberates the gas; all gas is discharged quickly pass through the coke layer and are exhausted out of the furnace body; and after the solid impurities in the gas are removed, the gas is quickly cooled and the condensable ingredient wherein is coagulated into bio-oil. The device comprises a fluidized bed and a moving bed; wherein, the fluidized bed comprises a wind inlet chamber, a wind distribution plate, amaterial inlet, a fluidized bed heat-exchanging surface, and the like; and the moving bed comprises a moving bed heat-exchanging surface, a coke hopper, a gas collecting chamber, and the like. The method has the advantages of simple disposal on raw material, little energy loss, low cost, rich oil production, high oil quality, and the like. The device integrates the functions of quick pyrogenationof biomass, deep cracking of coke, catalysis and modification of condensable gas, high-efficiency separation of gas and solid, and the like into a whole, and is suitable for various biomass pyrolysisliquefaction systems.