The analysis of the vehicle crash performance is of great meaning in the vehicle design process. Due to the complexity of vehicle structures and uncertainty of crashes, the analysis of vehicle crashworthiness is generally depending on the researchers' experiences. In this paper, different deformation modes of energy absorption components are studied. More specifically, the bumper, crash box, the front longitudinal beam and the engine/firewall have different frequency characteristics in the deformation process. According to these characteristics, it is possible to identify the performance of each component in the crash process of assembled structures. To achieve this goal, the crash response of the passenger cabin is decomposed by the time-frequency transformation. Different frequency components exist mainly in a specified period of the crash process. By comparing the features of each period and structural components, the relationship between the components and the crash responses of vehicle is identified. As an example, a frontal crash of Toyota Yaris at 56km/h is introduced for demonstration. The identified performance of each component is consistent with the real crash test and Finite Element simulation, which shows the effectiveness of the proposed method. Another two cases are also given for further discussion. The main advantage of the proposed scheme is that only the passenger cabin deceleration signal is used and the crash performance of a complex structure can be identified accurately. This is helpful in the vehicle design, crash tests as well as accident analysis.