The selection of foundation pit support schemes and parameters for subway stations critically impacts construction safety. This study develops a deep foundation pit support evaluation system, integrating subjective weights (Analytic Hierarchy Process) and objective weights (entropy method). A game theory-based combined weighting method and joint cloud model are constructed for optimal support scheme selection. Structural redundancy theory is employed to assess safety stability. Results demonstrate that game theory-enhanced combined weighting improves multi-attribute decision-making accuracy and model stability. The proposed model identifies the optimal diaphragm wall-internal support scheme, aligning with actual engineering designs, validating method reliability. During excavation, deep horizontal wall displacement and surface settlement outside the pit exhibit parabolic and "groove-shaped" patterns, respectively. Steel support axial force initially increases then decreases. Failure of the fourth-layer steel support significantly amplifies pit displacement and settlement, with redundancy dropping below other layers, indicating the lowest-layer support as a critical "weak component" requiring prioritized design and construction attention. These findings enhance safety evaluation precision and inform risk mitigation strategies for deep foundation pit engineering.