In order to obtain the stiffness-damping feature of cross-arm damping seat of special vehicles, the dynamic simulation model of cross-arm seat is established. The time-frequency responses on the level D road and different vehicle speed conditions（5 km/h, 15 km/h, 25 km/h and 35 km/h） are analyzed. With considering the weighted root-mean square（RMS） acceleration in criterion ISO 2631-1:1997 as an evaluation index, the ride comfort of the seat with different matching relationships of stiffness and damp are discussed. Furthermore, the real vehicle validation experiment is conducted. The results show that the seat vertical acceleration under different speeds has the non-stationary random characteristic. The seat vibration intensifies with the increase of the speed. Under different vehicle speed conditions, the first two model frequencies for the seat concentrates in 3 Hz～10 Hz, which includes the human sensitivity frequency ranges, inducing the poor ride comfort performance. Additionally, the simulation results agree with the experimental data, which verifies the correctness of the dynamic simulation model. The research has certain reference for multi-objective matching optimization design about the stiffness-damping parameters for the seat comfort of special all-terrain vehicles and engineering applications.