In order to solve the problems such as excessive deformation and instability in the process of shallow tunnel construction in water-rich and weak strata using subsurface excavation method, based on the project of Changsha metro line 5, horizontal advance support test was carry out, the Larson steel plate with positive and reverse adjacent lines was arranged in the outer profile of the tunnel section. The support effect of steel plate reinforced section was simulated using ABAQUS finite element software. The results show that the anti-deformation ability of the initial support structure of the tunnel can be effectively improved, the stability of the tunnel surface during excavation is also enhanced. Consequently, the subsidence deformation of the surface and the pipeline will be reduced significantly. The effective pre-support can be achieved using this method.