The invention relates to an extrusion forming method of J-shaped steel, and belongs to the technical field of an extrusion forming technology and profile manufacturing. The method solves the problemsthat the surface quality of J-shaped steel prepared by using a forming method in the prior art is poor, and the size precision cannot meet the requirement. The extrusion forming method of the J-shapedsteel comprises the following steps that extrusion equipment extrudes a blank; the blank enters a J-shaped glass cushion; and the blank enters an extrusion die with a J-shaped through hole. Accordingto the extrusion forming method of the J-shaped steel, the effect that the J-shaped steel is produced by using the die through a hot extrusion forming method is achieved.