Car hinge profile steel is one kind of hot rolled section steel connecting automobile body and door. The current market common manufacturing process has two kinds of stamping and hot rolling. The main function of the car door hinge is to connect the door and the body, and keep the position of the door relative to the body. That is to facilitate the opening and closing of the door, and the door hinge is composed of at least two parts, one is the body parts connected with the body, the other is the door parts connected with the door. According to the position, it is divided into: body parts, door parts, etc., and according to the structure, it is divided into: page board, rotary arm, etc.