The numerical simulation method based on software FLAC^3D for the large-diameter long pile is discussed, and the influences of parameters of soil-pile interface on the numerical results are analyzed. The results show that the inner friction angle and cohesion on the pile side have great influences on the bearing behavior of the pile, while a critical value exists for the influence of shear stiffness. It is required in the calculation to consider: under a horizontal load,the influences of parameters of pile side interface on the friction between the pile and pile side soil ； under a vertical load,the changes of shear stiffness coefficient with depth ； and under a inclined load,the shearing effect of the soil on the pile end