The invention provides a grinding-polishing device and a grinding-polishing method. The grinding-polishing device comprises a support part; a grinding-polishing part for grinding and polishing a workpiece, wherein the grinding-polishing part can be movably arranged on the support part and adjust the relative position with the support part according to the suffered action force from the workpiece, thereby enabling the grinding-polishing part to contact the workpiece to perform the grinding-polishing. The grinding-polishing device cancels the hard limiting mounting mode in the prior art, so that the grinding-polishing part can enable the grinding-polishing device to perform the grinding-polishing operation always clinging to the workpiece by adjusting the self-polishing position, guarantees that the ground and polished workpiece performs the grinding-polishing operation always under the effect of a certain of constant force, and the grinding-polishing effect of the grinding-polishing device is improved.