Abstract: In the foundation pit in which the engineering piles are constructed first and then excavated, the rebound deformation of the soil at the bottom of the pit in the process of excavation and unloading will lead to the upward displacement of the soil at the bottom of the pit relative to the piles. At this time, the piles may be broken due to large tensile force, which will greatly reduce the bearing capacity of the foundation. Based on an underground comprehensive pipe gallery project in Guizhou, the construction process of excavation of foundation pit is simulated by using the finite element software MIDAS GTS NX, and the influence laws of length and elastic modulus of the piles on the stress and deformation of the CFG piles are studied. The results show that the length of the piles has obvious influences on the stress and deformation of the CFG piles, and the influences decrease significantly when the pile length exceeds a certain range. Increasing their elastic modulus will make the piles bear greater tensile stress, but it can make them be in a safer state.