Abstract: In light of that traditional anchor-shotcrete support is difficult to adapt to large deformation of soft rock tunnel, the steel arch and shotcrete supporting structure is divided into two work stages: individual work stage of steel arch and combination work stage of steel arch and shotecrete. The mechanical behaviors and the mechanical effects of solid web steel arch and spatial steel truss arch in individual work stage are analyzed by using SAP2000 finite element program. Considering the material nonlinearity and geometric nonlinearity, the ultimate bearing capacity and deformation capacity of steel arches under different support conditions are studied. The results show that: (1)It is feasible for the steel arch to work alone as a support stage; (2) lateral support and restraint of arch springing have a decisive influence on action effect of the solid web steel arch; (3) the overall stiffness of the spatial steel truss arch is higher than that of the solid web steel arch, and it is less affected by lateral support; (4) the methods to im? prove the bearing and deformabilities of steel arch are proposed to provide more time and space for the implementation of shotcrete and other support measures.