Abstract: The silty soil and silty clay samples of 2~12 m-deep soil layer of the Minxian Seismic Station and the Qingyang Loess Plateau are studied by the dynamic triaxial and scanning electron microscopy experiments, and the dynamic elastic modulus and microstructure characteristics are measured. The dynamic constitutive relation of silty clay is studied. The relationship between the vertical structure of the loess and the transverse (perpendicular to sedimentary direction) and the maximum dynamic elastic modulus are studied by the correlation analysis method. The results show that the dynamic constitutive relations of silt and silty clay are consistent with the Hardin-Dinevich hyperbolic model. The influences of fractal dimension, probability entropy and average shape coefficient on the maximum dynamic elastic modulus of silt and silty clay are the most sensitive. Secondly, for the average circumference, long axis and short axis, the average area has a relatively small impact on them. In view of the vertical and horizontal correlations of silt, the influences of transverse microscopic parameters on the maximum dynamic elastic modulus are more sensitive. For the silty clay, the influences of vertical microscopic parameters on the maximum dynamic elastic modulus are more sensitive.