Abstract: To address the issues of high risk of block falling at the vault and low construction efficiency in traditional initial support technologies for super-large cross-section tunnels under complex geological conditions, this study investigates the mechanical characteristics and engineering applicability of the steel corrugated plate-steel frame composite initial support structure. Numerical simulations and model tests are conducted to validate its safety, deformation control capability, and synergistic bearing mechanism. The results indicate that: (1) The composite support performs similarly to traditional shotcrete-steel frame support in terms of surrounding rock deformation control and structural stress response. (2) It exhibits a higher failure threshold and smaller crack propagation range, with significantly enhanced structural integrity. (3) The corrugated plate demonstrates a differentiated stress mechanism, with compressive stress dominant at the peaks and tensile stress dominant at the valleys. (4) The axial force in the corrugated plate is primarily tensile; at the vault, the axial force increases to a peak tensile value and then decreases, eventually transitioning into compression. This composite structure offers both excellent support performance and high construction efficiency, making it suitable for soft rock, fractured zones, and rockburst-prone strata.