The method of FRF-based system synthesis(FBS)mentioned in this paper is introduced to predict the road induced noise before prototype vehicles are produced. With its help, the development cycle and cost of cars are greatly reduced. The full vehicle frequency response functions can be obtained by test method as well as CAE method, which avoid the establishment of trimmed body model. Besides, it could improve the efficiency and the computational accuracy at the same time. The end result was verified to be relia- ble after comparing calculated data with measured data.