Abstract: In the practical operation of plate-and-tube heat exchangers in a solid sandwich, the heat transfer efficiency may be reduced due to factors such as non-isothermal backing plates, diverse tube types and contact thermal resistance. For this reason, this paper proposes a general numerical analysis method for plate-tube heat exchangers employing contact structural feature correction. Firstly, the heat transfer process at the plate-tube interface under varying conditions is analyzed. A heat flux model is established for both D-type contact and embedded tube contact, key parameters relevant to structural heat transfer characteristics are extracted, and detailed derivations are provided for calculating heat transfer pathways, thermal resistance, and contact coefficients. Secondly, addressing technical challenges such as non-isothermal backplates, non-linear variations in contact thermal resistance, and structural coupling characteristics in plate-tube heat exchangers, a structural unitization numerical analysis strategy employing the superposition parameter method is proposed. This achieves unified modelling of multi-zone heat transfer characteristics and enhances computational accuracy. Subsequently, a universal numerical model system is constructed, with its accuracy and stability validated through forced convection heat transfer experiments. Finally, a functional relationship model was established for the contact region characteristic coefficient k_\mathrmbg . Combined with simulation results, sensitivity analysis validated the proposed method's effectiveness in modifying complex contact structures and enabling green energy-saving design.