The 1920 Haiyuan earthquake of 8.5 magnitude in Ningxia Province triggered the large-scale liquefaction and sliding of saturated loess on the Shibeiyuan tableland in Guyuan City, causing substantial casualties and property losses. Based on field investigations, engineering geological surveys, laboratory dynamic triaxial tests, and microstructural tests, the dynamic characteristics and microstructural parameters of saturated loess at a depth of 15-40 m in the sliding zone were investigated in this study. The results indicate that the constitutive relation of deep saturated loess aligns with the Hardin-Drnevich hyperbolic model. The dynamic shear modulus ratio of saturated loess decreases with increasing dynamic shear strain, whereas the damping ratio follows a logarithmic growth trend. Microstructurally, shallow saturated loess exhibits loose particle arrangements with large pores. With increasing depth, particle packing becomes denser, transitioning from overhead pore structures to interlocked pore configurations. The maximum shear modulus of saturated loess decreases with increasing initial void ratio but increases with increasing clay content. The maximum damping ratio, which characterizes the energy dissipation of saturated soil, gradually decreases with rising dry density and clay concentration. These findings provide foundational data for understanding liquefaction mechanisms and mitigating hazards in saturated loess regions.