The feature of this invention is that electrode is concurrently used as plating bath. The piece being plated (or anode) is put at the center in plating bath. The diamond granules is compactly filled into the cavity of plating bath. The two ends of plating bath are plugged with insulating plugs through which only diamond granules can not pass but plating liquor can pass. The plating liquor is flowed in from one end of plating bath, after workpiece has been plated, plating liquor is flow out from another end. At same time, the electrode flake which is connected with piece being plated (or anode) and installed on end plug is switched on power supply until the workpiece is plated to a definite shape. This invention makes the process for plating of diamond cutter being simplified, and with high speed and high quality of plating.