Abstract: This paper takes Zhengzhou-Xi’an highspeed railway(350km/h) as the object of the study,a large number of undisturbed loess samples in Huayin,Tongguan,Lingbao and Yanshi sections have been collected,based on the dynamic triaxial test of those samples,the relevant dynamic parameters of loess such as dynamic elastic modulus,dynamic damp and remains strain were provided.Furthermore,the numerical model of highspeed railway loess foundation is established;eight artificial seismic waves(10% and 2% exceedance probability in 50 years) are made according to the seismic risk analysis results,and then put them into dynamic model to calculate the deformation of loess foundation.The results show that both the horizontal and vertical deformations of loess foundation increase with the earthquake force,ultimately resulting in the slip and seismic subsidence of loess.It agrees with the results of field making-seismic test and dynamic triaxial test.The present result is the basis of the anti-seismic subsidence and antislide designs,and some feasible foundation treatment measures are bring forward and used in the design and construction of this highspeed railway.