Being noise resisting, the said tuning means needs no special soundproof room. It has detecting unit, freq-comparing unit and control unit contained in micro-computer frame. Practical freq detected by sensor is compared with standard freq to find out freq difference. Tuning is that the automatically-controlled metal remover removes the metal in special part of tuned tooth according to the equivalent pulse number from control unit so as to make the inherent freq of tuned tooth approach standard freq.