Abstract: Decks with large rectangle openings often have stress concentration problems at corner regions，and such a problem can be alleviated through planting ring plates along the inside edges. In this paper， a parametric study based on the structural finite element method is implemented to investigate the strengthening effects of ring plates with different sizes, namely plate thickness, width, and length， on deck opening corners with different thickness, opening sizes， and corner radius. It is seen that the Stress Concentration Factor (SCF) decreases first and then increases with the growth of the ring plate size, and only ring plates with reasonable scantling can alleviate the stress concentration effectively. An optimum design of ring plates is presented accordingly. Both the formula and design diagrams are proposed to calculate the optimum dimensions of ring plates, which serves as a good reference for future design on reducing the stress concentration for opening corners.