Steel beam shaped like Chinese character'mu '

The utility model discloses a steel beam shaped like a Chinese character'mu ', which comprises a beam body and brackets respectively arranged at two ends of the beam body and used for being connected with a building structure, the beam body comprises a web plate, a lower flange plate, an upper flange plate and a middle flange plate, the web plate is welded with the web plates of the brackets, the lower flange plate is welded with the lower flange plates of the brackets, and the middle flange plate is welded with the lower flange plates of the brackets. The upper flange plate is welded with the upper flange plate of the bracket through the upper cover plate, and the middle flange plate is welded with the middle flange plate of the bracket through the internal partition plate; the connecting ends, corresponding to the beam body, of the brackets are arranged in a step shape which is gradually contracted inwards from bottom to top. And the positions of welding seams between the upper cover plate and the upper fla