The dynamic stiffness of body-in-white joints has a great influence on NVH (Noise, Vibration and Harshness) performance of the vehicle. The analysis of the dynamic stiffness of the key joints of the body and subframe can provide a theoretical reference for the improvement of NVH performance in forward development of vehicles. On the other hand, it can shorten the development cycle and reduce the development cost. Taking an SUV model as the research object, this study proposed an optimization analysis method for the dynamic stiffness of the body-in-white structure at the key attachment points in the development and design stage, which was based on sensitivity analysis, and raised the average dynamic stiffness of the installation points to more than 8000N/MM. Firstly, the finite element model of the body in white is established, and the modal analysis and dynamic stiffness analysis are carried out by using the Optistruct structure solver in the simulation software to calculate the IPI curve of the body attachment point. Secondly, the dynamic stiffness curve of the target value is drawn and compared with the calculated IPI curve. The average dynamic stiffness values of each installation point in X, Y and Z directions were calculated. Then, according to the comparison results, direct frequency response analysis was used to find out the reason why the peak value of Y-direction IPI curve of the left rear shock absorber installation point was too high. Finally, combined with the sensitivity analysis of plate thickness, the optimization scheme of body structure size optimization and shape optimization is proposed for the relatively weak area. Through verification, the average Y dynamic stiffness of the left rear shock absorber installation point reaches the design target value. After optimization, the dynamic stiffness of the left rear shock absorber installation point Y is greatly improved, which provides an important theoretical basis for the subsequent design of the body in white, so that it can meet the target requirements of engineering design.