The traditional p-y curve method for analyzing the dynamic behavior of pile foundations in loess during strong earthquakes does not simulate the pile foundation structure, so the relevant dynamic parameters of the pile foundation in loess are inaccurate. In this paper, we present a new dynamic analysis method for pile foundations in loess during strong earthquakes. We designed a hardening soil-small (HSS) constitutive model based on the hardening soil (HS) model, and obtained the related parameters of the pile foundation in loess during strong earthquakes through the constitutive model. Then, using PLAXIS software, we constructed a finite element model of the pile foundation in loess. Based on these two models, we conducted experiments on pile foundations during strong earthquakes to analyze their horizontal displacement responses and the internal forces in the pile body under the coupled load. The experimental results show that the proposed method can accurately analyze the dynamic characteristics of pile foundations in loess during strong earthquakes.