Abstract: This paper addresses the issue of excessive second-order vibration of the driver's seat under idling conditions during the prototype stage of a certain vehicle model, in which the vibration at the lower part of the seat cushion was significantly greater than that at the upper part. Experimental tests were conducted to quantitatively measure the vibration response in the primary vibration direction of the seat, and modal analysis was performed at the upper and lower positions of the seat cushion. The results indicate that the main cause of the seat judder is the resonance between the second-order natural frequency of the driver's seat and the engine idling frequency. On this basis, a CAE model of the seat was established and correlated with the experimental modal results. Targeted structural optimization schemes were then proposed and implemented through engineering modifications by the supplier. As a result, the second-order judder of the driver's seat under idling conditions was effectively eliminated.