In the seismic design of pile foundation, current research mainly adopts the theory of auxiliary experiences engineering design methods. In particular ground, the pile must be specially designed to meet the seismic requirements. In this paper, with large scale finite element software ADINA,a 2-d finite element entity model is established to calculate and analyze the influence of soft soil to the dynamic interaction of soft pile-soil under the earthquake. The maximum displacements and acceleration of the measuring points on the pile are analyzed in different thickness and position of the soft soil. Calculation results show that: Soft soil effect the maximal displacement and acceleration of the measuring points on the pile which changed with the different thickness and positions of the soft soil. It should be noticed in the design of pile foundation and ground treatment.