The article points out that soil nail is soil anchor, soil nail wall is spray anchor support in soil layer. Ground excavation project exists stress redistribution, seepage field redistribution process, in general, with the excavation closely followed by the support, so the limit equilibrium design method has a large error, the paper introduces the guiding principles of the CSC method, soil nail wall force analysis, and concludes that the reinforcing steel mesh, spray concrete and soil anchors (soil nails) is the supporting structure of the matching. The paper further shows that the nonlinear large deformation theory of soft rock or soft soil ground excavation engineering is an effective tool for solving process problems.