The invention discloses a polishing machine for a valve body. The polishing machine comprises a lower bottom plate; a support is fixed to the upper end of the lower bottom plate; polishing devices are symmetrically mounted at the left end and the right end of the support respectively; a lower part positioning tool is fixed to the upper end of the lower bottom plate; a first air cylinder is mounted at the upper end of the support; an upper part positioning tool is fixed to the lower end of the first air cylinder. The polishing machine for the valve body has the advantages of being reasonable in structural design, convenient to use and the like. By means of the adjustable polishing wheel design, the inner wall of the valve body is polished through cooperation of a spring with a supporting plate, the polishing efficiency of the valve body is improved, the polishing quality of the valve body is guaranteed, and the manpower and material resources are saved.