Based on the analysis results of the whole ship structure of a large luxury cruise ship, the typical upper-built side door and window types are selected, the strength of the fine model is analyzed, and the structure of the high-stress area is optimized. Based on the envelope value load method of the LR classification society passenger ship code, the finite element model and mass model of the whole ship are established, and the ShipRight software is used to load and level the whole ship. The unit bending moment and unit shear force are used to correct the stress results. Finally, the structural response of the whole ship is obtained, and the stress distribution characteristics of the main supporting structure of the whole cruise ship are analyzed. Based on the results of the coarse mesh, the detailed model calculation is carried out for the side door and window structure to obtain the detailed stress distribution law of the opening structure, and the method of adding insert plates is adopted to strengthen the position where the stress exceeds the specification. After structural optimization, the corresponding regions meet the strength requirements. The research results can provide a reference for the finite element calculation of the passenger ship and the design of the side windows and doors of the superstructure.