Rectangular damping blocks are commonly used auxiliary energy dissipation structures in spillway stilling basin. However, the current damping blocks design specifications lack explicit principles and methods for design. Therefore, this study employs numerical simulation methods to analyze the hydraulic characteristics and energy dissipation patterns of stilling basin equipped with multi-row rectangular damping blocks, with the area ratio of the rectangular damping blocks is 4%, 6%, 9%, and 15%. The research is set against the backdrop of an actual spillway project. The results indicate that when the area ratio of the rectangular damping blocks exceeds 6%, the energy dissipation rate of stilling basin increases approximately linearly with the number of damping blocks. When the area ratio reaches 15%, the energy dissipation rate in the stilling basin exceeds 60% under various flow conditions.