The invention discloses an extrusion forming device for an aluminum alloy product. The extrusion forming device comprises an upper die plate, an extrusion die body and a lower die plate. A material passing middle hole, two pairs of material passing side holes and two material passing tail holes are formed in the upper die plate. The extrusion die body comprises an extrusion middle portion, two extrusion front portions and two extrusion rear portions. A material containing groove is formed in the lower die plate. An extrusion hole is formed in the bottom of the material containing groove. Two arc grooves are formed in the extrusion middle portion. The first ends of the two arc grooves communicate with a first clearance, and an interval is formed between the second ends of the two arc grooves. According to the above extrusion forming device for the aluminum alloy product, the upper die plate, the extrusion die body and the lower die plate are arranged and the upper die plate is matched with the lower die plate, so that an aluminum material enters the extrusion die body and is extruded out according to a preset extrusion route, and the aluminum alloy product is obtained.