The pressure excitation on the front window surface of the vehicle is an important indicator of unsteady flow and aerodynamic noise in the front window area. The complex unsteady flow in this area produces a larger scale vortex structure, which leads to complex unsteady pressure excitation on the front side window surface. In this paper, the turbulent pressure and acoustic pressure excitations on the front window surface of the vehicle are obtained by the hybrid Computational Aeroacoustics（CAA） method based on Acoustic Perturbation Equations（APE）. The Dynamical Mode Decomposition（DMD） is introduced to analyze the pressure excitation on the front side window surface, which demonstrates that the turbulent pressure excitation has the frequency-based regional distribution characteristics and the acoustic pressure excitation acts as radiation sound field characteristics. The turbulent pressure excitation, acoustic pressure excitation and the relative contributions of different excitation sources to the car interior noise are discussed. The main turbulent pressure excitation on the front side window surface identified by the DMD is generated by the wake vortex shedding of the rear view mirror trail. Its characteristic frequency is 59 Hz, which is consistent with the experimental measurement results and it also verifies the validation of the turbulent pressure excitation calculation results. Comparing the DMD modes of the turbulent pressure and acoustic pressure with the same frequency in the space section of the front side window region, the main sound source position in the front side window region is identified. One is located at the pedestal of the rearview mirror, which is generated by the convection of the pedestal vortex in this region. The other is located at the lower edge of the mirror body, resulting from the separation vortex in this area. The latter is identified by the microphone array in the wind tunnel test，which validates of the estimation of the acoustic field.