The rise of groundwater level can reduce soil’s effective stress and destroy it’s structure. As a result, the dynamic characteristics of pile-soil-structure system will be changed remarkably. In this paper, a structural dynamic model was used for saturated loess, and the finite-infinite element model of pile-soil-structure system was established to study the groundwater level’s influence on the system’s dynamic characteristics, which included the distributions of pile section’s shearing stress, horizontal displacement and acceleration. The results indicated that, the height of groundwater level did not change the distribution shapes of shearing stress, horizontal acceleration, but had effect on their values. To the top section’s shearing stress and horizontal displacement, there almost had a same dividing groundwater level. When groundwater level was higher than that one, the shearing stress and horizontal displacement were increasing with the rising of groundwater level, but the regulations were just opposite when groundwater level under that height. The study also shown that, to a determinate geological condition and pile foundation, there has a dividing groundwater level, and which is also the most secure level to the pile-soil-structure system. The conclusion can give theoretic instruction for the safety evaluation of pile-soil-structure system around water area.