［Objective］When using sequential excavation methods such as central diaphragm walls and double-side heading techniques to construct large-span mined metro tunnels, temporary supports often hinder the effective use of large-scale mechanized operations. To meet the requirements of low-vibration mechanized construction in environmentally sensitive areas, it is necessary to develop the SAWS (superimposed arch wall system) method for large-span mined tunnel excavation and support, and to study its key technologies.［Method］After a brief introduction of SAWS (superimposed arch-wall support) method, taking a large-span single-arch mined metro station in Chongqing soft rock formation as an example, a numerical model is established using FLAC 3D software to simulate and analyze the geotechnical and structural mechanical behaviors during the entire station excavation process. A comparative analysis is conducted between Method 1 (conventional double-side heading method) and Method 2 (SAWS method) in terms of land subsidence, distribution of plastic zones in surrounding rock, deformation of initial support structure, stress in initial support structure, and axial force in system anchors, in order to verify the applicability and reliability of SAWS method.［Result & Conclusion］Compared to the double-side heading method, the SAWS method results in a maximum land subsidence increase of approximately 12.4%, in a maximum arch vault settlement of 8.5%, and 26.0% in maximum horizontal convergence within the tunnel along the direction perpendicular to tunnel line, all of which remain within safe margins. The internal force at the arch foot of the initial support is reduced by about 42.9%, and the axial force of system anchors in side wall middle and lower parts decreases by approximately 20.0% to 30.0%. The arch invert heave and the distribution of plastic zones in surrounding rock are essentially the same for both methods. SAWS method demonstrates sufficient safety and reasonable stress distribution in the initial support and anchoring structures. It can meet the requirements for large-scale mechanized construction and is feasible for implementation.