Abstract: A mode transition scheme for a tandem TBCC inlet was proposed, which utilizes a translating splitter plate to realize flow-path switching. Three geometric profiles of the transition device, namely convex, triangular, and concave,were designed. Two-dimensional numerical simulations were performed to investigate the flow field and aerodynamic characteristics of each profile during mode transition under different geometric parameters (radius of curvature R₁ for Configuration A, inclination angle θ for Configuration B, and radius of curvature R₂ for Configuration C). Taking the comprehensive optimization of the total pressure recovery coefficients for the turbine and ramjet flow paths as the selection criterion, the variant of configuration A with R₁=0.30Rₑ (where Rₑ denotes the inlet exit radius) is selected as the optimal geometric profile-parameter combination and adopted as the baseline configuration for subsequent back-pressure characteristic studies. Numerical results under full operating conditions demonstrate that the proposed scheme can effectively control the opening and closing of the ramjet flow path, and can precisely coordinate the flow distribution between the two flow paths via their back-pressure regulation to meet the operational requirements of the downstream engine.