The invention discloses a grinding, positioning, cutting and automatic bending machine for steel machining. The grinding, positioning, cutting and automatic bending machine comprises a bearing plate,an installation frame and a U-shaped groove. The installation frame is installed on the upper wall surface of the bearing plate, and a grinding unit is installed on the lower wall surface of the installation frame. The U-shaped groove is formed in the upper wall surface of the bearing plate and is located on the right side of the grinding unit. A cutting unit is installed on the upper wall surfaceof the bearing plate and is located on the right side of the U-shaped groove, and a bending unit is installed on the upper wall surface of the bearing plate and is located on the right side of the cutting unit. A steel bar is transported to a device by a conveying mechanism, the surface of the steel bar is polished by a rotating polishing mechanism, the problem that the surface is rusted, the artificial rust removal time is longer and the efficiency is low due to the fact that the steel bar is placed for too long is solved. The position, needing cutting, of the steel bar is located through apositioning mechanism, the executive mechanism is controlled to perform cutting and the problems that as for the steel bar cutting, certain danger exists in the artificial cutting, the cutting lengthis different, and the use is affected is solved.