For the excavation work of sandy soil at a high ground water level, it is required to investigate the danger of boiling failure normally by using the Terzaghi method is based on an experimental model that doesn't have the head loss of seepage at the back of retaining walls above the bottom of excavation, however, it doesn't necessarily ensure reasonable design of retaining walls for deep excavation. Therefore, we applied the FEM method to analyze the seepage of a model excavation ground. This paper describes the effect of the excavation depth, width and other factors on the pore water pressure distribution.