The invention discloses a biomass pyrolysis gasification and tar catalytic cracking device and method and belongs to the technical field of biomass energy utilization. The device comprises a hopper, a feeding system, a biomass pyrolysis gasification system, a tar catalytic cracking system, a fluidized bed coke combustion system, a hot sand separation system, a fluidized bed catalyst regeneration system and a catalyst separation system, wherien the biomass pyrolysis gasification system comprises multiple cyclone reaction separators and is used for obtaining hydrogen-enriched synthesis gas through a high-efficiency gasification reaction of the biomass raw materials under the gasification medium and fully reacting the biomass raw materials; and in addition, the tar catalytic cracking system comprises multiple cyclone reaction separators and is used for performing high-efficiency tar catalytic cracking, so that the tar is fully reacted so as to obtain hydrogen-enriched synthesis gas with extremely low tar content, and the inactivated catalyst is timely discharged out of the catalytic reaction system. According to the device, due to the introduction of the multi-stage cyclone reaction separators, and high-efficiency biomass gasification and high-efficiency tar conversion can be realized, so that the hydrogen-enriched synthesis gas with the low tar content is obtained.