Transfer path analysis is now the most common tool in noise and vibration diagnosis of a mechanical system. In order to avoid the limitations of the existing TPA methods, a novel transfer path analysis method is proposed base on the FRF(frequency response function)-based substructure dynamic characteristic identification theory. It is applied to a simplified finite element model used to simulate the powertrain and the body of a car. The dynamic characteristics of the substructures in free state and the joint properties are obtained in coupled condition by a spectral-based inverse substructuring approach. And then the coupled system behavior can be described in terms of the free substructure FRFs and coupling dynamic stiffness by FRF-based substructuring approach. Thus, vibration path contribution analysis is carried out and the dominant paths and substructure FRFs are identified.