A biomass pyrolysis device and a biomass pyrolysis method is for optimal matching of thermal energy and microwave energy, wherein the device comprises a power generation system, a drying device and a microwave pyrolysis device; wherein the drying device is a cylinder nested with a flue gas layer and a material layer, a material inlet of the drying device is connected with a feeding device, and a volatile outlet is connected with a condensing unit; the microwave pyrolysis device is connected with a material outlet of the drying device, and a pyrolysis gas outlet of the microwave pyrolysis device is connected with the condensing unit; the condensing unit is connected with the power generation system, and waste gas generated by the power generation system is introduced into the flue gas layer of the drying device.