The method relates to the technical field of glass product annealing, and particularly discloses a foam glass blank annealing device. The device comprises a bottom plate, an electric motor, an annealing mechanism and a feeding mechanism, wherein the annealing mechanism comprises a screw cap, a heating device located in the spiral center of the screw cap and an exhaust fan; the screw cap is made ofa thermal insulation material and buckled on the bottom plate to form a closed spiral space with the bottom plate, air holes are formed in the side wall of a ring with the minimum diameter of the screw cap, a foam glass discharging port is formed in the end with the maximum diameter of the screw cap, and the exhaust fan faces the discharging port and acts on the inside of the screw cap; the feeding mechanism comprises a vertical telescopic cylinder, an output end of the vertical telescopic cylinder is connected with a feeding plate, and a push plate is glidingly connected onto the feeding plate; a feeding port matched with the feeding mechanism is formed in the bottom plate constituting the spiral space, and a wedge rod matched with the push plate is further arranged on the screw cap. With the adoption of the technical scheme, the problem of large space occupied by the conventional foam glass blank annealing device can be solved. Therefore, the device can be widely applied to foam glass annealing.