Based on scheme of Dalian gulf cross-sea bridge, in this paper, a 3-dimensional FE model for Self-anchored cable-stayed suspension bridge is established with finite element program and pile-soil-structure interaction is simulated by use of the equivalent embed fixation model. Based on the FE model, model analysis is carried out and the effects of pile-soil-structure interaction on dynamic behavior of long-span self-anchored cable-stayed suspension bridge are specially studied. The seismic response analysis result considering that pile-soil-structure interaction was compared with that of without considering such interaction. The analysis result show that interaction extend the nature period of structure, has the greatest impact to the first vibration mode; meanwhile, enlarged longitudinal displacement and moment of stiffening beam in middle of main span, longitudinal displacement on top of tower and axial force at bottom, but reduced the moment of tower at bottom. The research results provide some theoretical foundation to composite structure system.