Abstract: The lateral ultimate soil pressure of the passive pile has not been completely solved, and many researchers have done studies of this problem. Using the explicit finite difference code FLAC(3D) (Fast Lagrangian Analyses of Continua), the lateral ultimate soil pressure of a single passive pile with pined-head and pined-tip condition and uniform soil movement was investigated, the Mohr-Columb elastic-plastic constitutive model was applied to a model for the non-linear stress-strain soil behaviour, the pile was assumed to have linear elastic behaviour, the interface model incorporated in FLAC(3D) code was used to simulate the soil/pile contact. The results given by the numerical analysis indicated that the soil pressure acting along the pile shaft increased with the soil movement increasing. While reaching the limit state, in the shallow soil the lateral soil pressure increased with increase of embedded depth, but in the deep soil the lateral soil pressure almost remained constant with increase of embedded depth. The roughness of the pile had an important influence on the lateral soil pressure. The relative stiffness between pile and soil had important influence on the displacement, shearing force, moment and lateral soil pressure of the pile. The shape of the soil pressure versus the relative soil-pile displacement curves and the magnitude of relative displacement to mobilize the ultimate soil pressure were analyzed. The research results are in good agreement with those reported by other researchers and better than the latter.