The utility model relates to a tool, in particular to a tool for controlling the thickness of a steel bar protection layer. The tool is characterized by comprising a positioning framework, wherein a T-shaped adjusting end which is perpendicular to the positioning framework and is provided with a thread is arranged in the middle of the positioning framework in a matching manner through a nut; the positioning framework is in an H shape formed by assembling two parallel vertical rods and the nut connected between the vertical rods, the T-shaped adjusting end is formed by welding a horizontal cross rod with a thread and an operating handle, and the horizontal cross rod is matched with the nut. The tool has the advantages of simple structure, low manufacturing cost, good convenience for application, reliable performance, good convenience for production, flexibility in use, good controllability and adaptability, and the like.