The present invention relates to a wheel polishing apparatus composed of a frame, motors, servo electric cylinders, a polishing head, guide rails and the like. A wheel is fixed onto the clamp on the platform, a motor I rotates the platform and the wheel via the main shaft, a motor II rotates the polishing head via the drive shaft; the canting servo electric cylinder can realize the relative movement of the polishing head along the contour line of the back cavity of the wheel via the canting guide rail, the horizontal servo electric cylinder can realize constant contact between the polishing head and the back cavity of the wheel via the horizontal guide rail. The invention can realize the function of automatically polishing the back cavity of the wheel, which has desirable effects and advanced process and high degree of automation, and is characterized by simple construction and low cost.