Surface and subsurface damage affect the preparation of high-resolution HgCdTe and CdZnTe detectors. Grinding experiments were performed on CdZnTe substrates with the grinding wheels of different abrasive sizes. The surface topography and subsurface damages of CdZnTe substrates ground by diamond grinding wheels with different grit sizes were studied. The effects of the grit sizes of grinding wheels on the surface topography and subsurface damage of CdZnTe substrates were discussed. The surface roughness and subsurface damage layer depth of CdZnTe after grinding with #3000 diamond grinding wheel are only Ra 7 nm and 100 nm, proved that grinding is of great potential for CdZnTe substrate processing.