Abstract: This article takes as an example the significant second-order vibration in the driver’s seat during idle operation at the prototype vehicle stage, where the lower end of the seat cushion exhibits more pronounced vibration than the upper end. Through the quantitative test of the vibration value of the main vibration direction of the seat, as well as the modes of the lowest and uppermost positions of the seat, it is known that the main reason for the shaking is the resonance between the second-order frequency and the idle frequency of the main driver’s seat under the idle condition. Combined with the CAE seat modeling, and benchmarking with the test mode, the optimization scheme was proposed. Finally, according to the optimization plan, the supplier provided an engineering restructuring plan for implementation, and finally solved the problem of second-order jitter of the main driver’s seat under idle conditions.