Abstract: The 2023 Jishishan Mw6.2 earthquake induced the liquefaction flow slip of loess in Zhongchuan Township. In order to reveal its low-angle long-distance slip mechanism, based on the dynamic triaxial tests and microstructure analysis of undisturbed saturated loess samples, the effects of confining pressure and dynamic stress amplitude on the changes of dynamic strain and pore water pressure are studied. The results show that the development of dynamic strain is characterized by three stages. The change of pore pressure is controlled by dynamic stress and confining pressure. Under low dynamic stress, the pore pressure increases slowly, and the liquefaction critical value is high. Under high dynamic stress, the pore pressure increases rapidly, and the liquefaction critical value decreases. The peak values of dynamic strain and pore pressure increase synchronously in the early stage, and lose synchronization in the later stage. The normalized analysis shows that the two have dynamic correlation. Microscopically, liquefaction destroys the overhead pore structure and promotes the pore connectivity to form a seepage channel. Quantitative analysis shows that the pore complexity increases and the shape regularity decreases. Dynamic load causes structural collapse, and enhanced seepage leading to, pore pressure rise and effective stress loss. Such synergistic strain development, ultimately triggers saturated loess liquefaction.