Based on the vibration problem of Some users light truck door frame,road load spectrum in similar pavement condition is obtained and extracted as the target signals.Including the doors,the multi-body dynamics model of cab suspension system is built so as to do virtual load iteration to get the real displacement driver of the cabin.By fixing the elastic element system features,more accurate system dynamic response is acquired.By means of structure optimization on the key points to ensure that the door frame dynamic response in all kinds of harsh conditions can meet users requirements.At the same time the scientific and reasonable method of product forward design is provided for the door system.