The aesthetic design is essential for the design of the luxury Ro-Ro passenger ship, and window design is one of the elements for the aesthetic design of luxury Ro-Ro passenger ships. However,large windows in public areas can meet the aesthetic design requirement, but impose challenges to the structural design. The fatigue strength of the opening corner of the large porthole has been studied for the 866 passenger/4 850 meter Ro-Ro passenger ship. The design method of the porthole in the specification is briefly introduced, and the basic method to reduce the fatigue stress of the porthole is presented in detail based on the finite element analysis of the whole ship. The alternative schemes are compared and analyzed. The optimal scheme is then selected to meet the fatigue stress requirement of the window frame, which theoretically prevent the fatigue crack of the window frame and the resulting glass breakage. It can provide reference for the design of the similar ships.