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, an optimization analysis method was proposed 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 8 000 N/mm. Firstly, the finite element model of the body in white was established, and the modal analysis and dynamic stiffness analysis were carried out by using the Optistruct structure solver in the simulation software to calculate the IPI(input point inertance) curve of the body attachment point. Secondly, the dynamic stiffness curve of the target value was drawn and compared with the calculated IPI curve, and the average dynamic stiffness value of each installation point in X, Y and Z directions was calculated. Then, according to the comparison results, the reason of the high peak value of the left rear shock absorber connection point Y direction IPI curve was found by direct frequency response analysis. Finally, an optimization scheme for the size optimization and morphology optimization of the body structure in the relatively weak area was proposed based on the sensitivity analysis of plate thickness. 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.