The invention discloses a reference ball rapid replacement structure. The structure comprises a strong magnetic seat, a reference ball rod and a reference ball. A containing hole is formed on the strong magnetic seat, and a fixed screw hole is formed on one side of the strong magnetic seat and is communicated with the containing hole; one end of the reference ball rod is inserted in the containing hole, and the other end of the reference ball rod is provided with a locating table; and a positioning hole is formed on the lower portion of the reference ball, and the positioning hole is matched with the positioning table in shape. By means of the reference ball rapid replacement structure, due to the fact that the reference ball and the reference ball rod are of independent structures, as for different workpieces, reference ball rods or reference balls with different heights are needed. The reference ball rod or the reference ball can be independently replaced, so that the structure is wider in using range, more convenient to replace and low in using cost.