The invention belongs to the technical field of foam board production equipment, and discloses a foaming device for an aluminum alloy foam board. The foaming device for the aluminum alloy foam board comprises a foaming box with box doors on the left side wall and the right side wall, an auxiliary foaming mechanism, a positioning groove and a feeding mechanism, wherein the foaming box is a rectangular box body formed by welding steel plates, the auxiliary foaming mechanism is arranged in the foaming box, the positioning groove is formed in the inner bottom wall of the foaming box, and the feeding mechanism is placed in the positioning groove. According to the foaming device for the aluminum alloy foam board, through the design of the auxiliary foaming mechanism, a plane with a unidirectional glass cover is utilized to be adhered to the surface of a board, and the resistance in the aluminum alloy foaming process is counteracted in the board foaming process by pressing the board, so thatbubbles are broken and the bubbles in the board are denser, the situation that large bubbles are formed to jack up the aluminum board is avoided, the problem of poor internal density uniformity afterthe board is formed is solved, and the realization of excellent performance of the aluminum alloy foam board is ensured.