Using the finite difference procedure FLAC3D to simulate the excavation process of a deep foundation pit by a double-row piles retaining structure, the paper analyzed the change of soil displacement fields in the excavation process. The studies showed that the space mechanics character of retaining structure and soils, the interaction between soil and retaining structure and the excavation procedure obviously affect the displacement and settlement of the retaining structure. The paper also discussed influence of stiffness change of soil between double-row piles on displacement and settlement, the displacement and settlement of lateral soil of foundation pit could be decreased by properly increasing the stiffness change of soil between double-row piles.