The invention belongs to the technical field of biomass pyrolysis gas treatment, and discloses a method and device for separating solid particles and tar in biomass pyrolysis gas. The method comprisesthe steps that pyroligneous liquid is sprayed into the biomass pyrolysis gas in the precipitating process, the pyroligneous liquid is gasified immediately to form steam at the high temperature, the steam combines with the tar in the pyrolysis gas to form a macromolecular oil-water miscible particles which are in sufficient contact with the solid particles in the pyrolysis gas, the solid particlesare adhered to the oil-water miscible particles and precipitate to the bottom of a settling chamber under the effect of gravity, and finally adsorbed by biomass carbon, and accordingly the high-quality biomass carbon rich in organic matter is obtained. The separation method greatly reduces the content of the solid particles and the tar in the pyrolysis gas, effectively avoids occurrence of the problem that a pipeline is blocked due to existence of the solid particles and the tar in a follow-up purifying device, the production cost lowered, and powerful guarantees are provided for continuous conduction of the biomass pyrolytic reaction.