A method for producing synthesis gas from biomass by pyrolysis, comprising: 1) pre-processing a biomass raw material, the pre-processing comprising crushing the biomass raw material to have particle sizes of 1 - 6 mm, and drying the biomass raw material until the water content is 10-20 wt. %; 2) performing pyrolysis on the biomass raw material by fast biomass pyrolysis technology In a pyrolysis bed, the product of the pyrolysis bed being a pyrolysis gas and a carbon powder; 3) separating the pyrolysis gas from the carbon powder and a cyclic solid heat carrier using a cyclone separator; wherein the cyclic solid heat carrier is used as heat source of the pyrolysis bed by using the heat generated by combustion of self-produced non-condensable pyrolysis gas; 4) separating the carbon powder away from the cyclic solid heat carrier via a solid-solid separator, feeding the carbon powder to a carbon powder stock bin for collection, heating the cyclic solid heat carrier in a carrier heating fluidized bed and conveying the cyclic solid heat carrier to the pyrolysis bed for recycling use; 5) conveying the generated pyrolysis gas to a condensate tank for spray condensation, condensing a condensable part in the pyrolysis gas to generate biological fuel oil, pressurizing the generated biological fuel oil by a high pressure oil pump and feeding to a gasification furnace to be gasified; and 6) feeding one part of non-condensable pyrolysis gas to a combustion bed to combust with air, conveying the other part of the non-condensable pyrolysis gas to the pyrolysis bed as a fluidizing medium, wherein the ratio of the non-condensable pyrolysis gas to air and the temperature of the carrier heating fluidized bed are controlled to make sure that the temperature of the pyrolysis bed is 400 - 600°C, and a residence time of gas phase in the pyrolysis bed is 0.5 - 5 s. 1) pre-processing a biomass raw material, the pre-processing comprising crushing the biomass raw material to have particle sizes of 1 - 6 mm, and drying the biomass raw material until the water content is 10-20 wt. %; 2) performing pyrolysis on the biomass raw material by fast biomass pyrolysis technology In a pyrolysis bed, the product of the pyrolysis bed being a pyrolysis gas and a carbon powder; 3) separating the pyrolysis gas from the carbon powder and a cyclic solid heat carrier using a cyclone separator; wherein the cyclic solid heat carrier is used as heat source of the pyrolysis bed by using the heat generated by combustion of self-produced non-condensable pyrolysis gas; 4) separating the carbon powder away from the cyclic solid heat carrier via a solid-solid separator, feeding the carbon powder to a carbon powder stock bin for collection, heating the cyclic solid heat carrier in a carrier heating fluidized bed and conveying the cyclic solid heat carrier to the pyrolysis bed for recycling use; 5) conveying the generated pyrolysis gas to a condensate tank for spray condensation, condensing a condensable part in the pyrolysis gas to generate biological fuel oil, pressurizing the generated biological fuel oil by a high pressure oil pump and feeding to a gasification furnace to be gasified; and 6) feeding one part of non-condensable pyrolysis gas to a combustion bed to combust with air, conveying the other part of the non-condensable pyrolysis gas to the pyrolysis bed as a fluidizing medium, wherein the ratio of the non-condensable pyrolysis gas to air and the temperature of the carrier heating fluidized bed are controlled to make sure that the temperature of the pyrolysis bed is 400 - 600°C, and a residence time of gas phase in the pyrolysis bed is 0.5 - 5 s.