The utility model discloses a reaction device for volume reduction by a radioactive organic solid waste heat method, and solves the problems of serious coking, material blockage and the like in a solid waste treatment process caused by unreasonable design of a device structure and a feeding mode of a fluidized bed in the prior art. The device comprises a fluidized bed reactor with a fluidized bedfeeding pipe, wherein the fluidized bed feeding pipe is connected with a spiral conveyor; and a cooling jacket with a cooling water inlet and a cooling water outlet is also arranged on the fluidized bed feeding pipe. According to the utility model, the problems of coking, material blockage and the like in the feeding process of the high-temperature fluidized bed can be effectively avoided, so thatthe operation flexibility of the solid waste feeding flow rate is higher.