Abstract: Drive system is a key system of radar. Abnormal sound is usually the forewarning of fault or abnormity of drive system. This paper carries out mechanical analysis for the abnormal sound of a radar drive system. Through checking the drive parts, adjusting the servo system parameters and feeling the whole system by ears, eyes and fingers, the reason of abnormal sound is given according to related vibration theory and the principle of energy accumulation and release. Verification is also carried out. The result and method of this paper can provide reference for solving the abnormal sound problem of similar drive system.