This invention relates to an improvement of a clip mechanism on a grinding cloth platform and the clip mechanism includes a jack post, a movable knob, and a clamp, mainly making a bottom side of the movable knob equally goes across the suppressed clamp at the two sides of the jack post of the clamp linking with a pivot, thereby providing a precise clamp force to the clamp; through a hexagonal combination covering hole, the clamp is put on a hexagonal driving portion of the jack post so as to disallow the clamp turn around the shaft and to make it stably downward move, thereby making the clamping tooth provided at its bottom side precisely align with the table board to clamp the grinding cloth for its location on the bottom side of the grinding cloth platform for smooth and stable grinding when a surface of an object is ground on the platform.