Soil nailing is one of the support pattern widely used today. It is useful to discuss the problem of the mechanism of soil nailing. The mechanism of action, deformation and stress state of the soil nailing were analyzed by using the finite element method. In the finite element model, the modified Goodman Jointed Element was adopted to simulate the interface between the steel bar and the rock or soil medium, and the Drucker Prager rule which reflects the Shear-Swell performance of the soil was adopted in the model，too. The comparison between monitoring results and inspecting in practical engineering examples shows that the soil nailing model is very effective and feasible，which turns out to meet the design requirements completely and has a wide application value in the design and construction in the soil nailing.
