In order to solve the problem that the traditional hydraulic shock absorber model can not reflect the influence of its dynamic characteristics on the dynamic performance of high-speed train,a dynamic model of yaw damper which included pressure cylinder,constant through hole,oil storage cylinder,oil return valve and unloading valve was established by using Simulink simulation software.The curve passing performance of 350 km/h EMU was analyzed with the dynamic simulation software SIMPACK.The results show that compared with the traditional piecewise linear model, the damping force calculated by the dynamic model of the yaw damper covers the viscous damping force and the recovery force generated by the oil compression, and the simulated indicator diagram is in good agreement with the experimental results, which can be used to accurately describe the dynamic behavior process of the yaw damper.The dynamic co-simulation results show that the snaking instability critical speed on the curve can be effectively increased by increasing the overheight of the outer track and the curve radius; once the train running speed exceeds the critical speed corresponding to the curve section, its derailment coefficient, overturning coefficient and wear index will increase sharply, which seriously affect the driving safety; the snaking instability critical speed of the 350 km/h EMU is about 220~260 km/h, 280~340 km/h and 335~400 km/h on the curves with the radius of 3 000, 5 000 and 7 000 m respectively.