This paper focuses on the idling resonance problem of a certain kind of vehicle. Based on the noise and vibration measurement technology, the three dimensional vibration transmission path and vibration sound coupling in the vehicle were analyzed. The reason of idling resonance was that engine lateral vibration was not reduced adequately by the mounting system, which caused the frequency coupling between the engine’s twice rotational frequency and the frame natural frequency. Optimizing the design of mounting system, the mounting rigidity and natural frequency of mounting system were changed.Vibration isolation performance was enhanced so as to improve the ride comfort of the vehicle.