The invention discloses a workpiece polishing detection device. The workpiece polishing detection device is composed of a support, a polishing head, a cylinder, a detection head, an installation plateand a laser distance measuring instrument. During work, the detection head is fixedly connected to the lower end of a piston of the cylinder, and when the cylinder moves to a lower limiting position,the detection head touches the surface of a measured workpiece to obtain position and posture data; a least square method is adopted to calculate a transformation matrix between a theoretical workpiece coordinate system and a machine tool coordinate system, and a step in which position and posture of the workpiece are adjusted is omitted; the laser distance measuring instrument is located under the polishing head in the Z direction and continuously scans the surface of the workpiece to obtain a polishing track at equal normal-direction intervals, the correctness of coordinate system transformation when the position and posture of the workpiece do not need to be adjusted is verified, the correctness of a numerical control program of polishing at equal normal-direction intervals is verified, and compatibility of the servo capability of the numerical control program of polishing and a machine tool is verified. Through the workpiece polishing detection device, the polishing technology auxiliary time is saved, polishing at equal normal-direction intervals during the polishing technology is ensured, and the reliability of removing through polishing, the controllability of the polishingquality and the polishing technology efficiency are improved.