A program of nonlinear finite element is developed to simulate the process of excavation in this paper. An excavation case is used to investigate the distribution and development of earth pressure behind or in front of a retaining wall. The influences factors on earth pressure such as consolidation, strut stiffness, wall stiffness and embedded length of the wall are studied. The difference between calculation and the field observation of earth pressure on retaining wall of an excavation of an excavation in Hangzhou are also analyzed.