Abstract: Silty fine sand is prone to liquefaction or seismic subsidence under vibration load, which leads to the risk of foundation instability. At the same time, the difference of fine particle content under hydraulic separation will also affect the spatial dynamic response of fine sand. In this paper, in-situ standard penetration and indoor dynamic triaxial tests were carried out on the silty fine sand of a beach reclamation foundation to explore the spatial distribution characteristics of the liquefaction of silty fine sand under the vibration load of the site, and to analyze the influence of silty fine sand on the liquefaction process of the foundation by changing the parameters such as magnitude, burial depth and fine particle content under seismic load. The test shows that under the action of site vibration load, the local fine sand has the possibility of liquefaction at the depth of 5 m, and the long-term and repeated vibration load in the site will affect the compactness of the fine sand and cause hidden dangers. Under the action of seismic load, the possibility of liquefaction of fine sand increases with the increase of seismic peak acceleration, but the strain development rate does not change with the buried depth in a single factor. Increasing the content of fine particles can effectively enhance the liquefaction resistance of fine sand. The research results provide theoretical support and basis for the foundation or similar foundation to take preventive measures to improve the anti-liquefaction strength.