Abstract: Currently, as sponge city construction continues to advance in China, optimizing the formulation strategy for the core indicator of annual runoff total control rate in sponge city development holds significant importance for balancing rationality and cost-effectiveness.By employing traditional engineering strategies superpositioned with the first-order change rate curve of the annual runoff total control rate for economic analysis, and validating it through runoff pollution control and drainage pipe design objectives, a "3+2" indicator formulation strategy for the annual runoff total control rate has been established.The proposed strategy comprehensively considers various factors, including the zoning map of the annual runoff total control rate, the relationship between the annual runoff total control rate and its first-order change rate curve, the principle of maintaining natural hydrological conditions post-urban development close to pre-development levels, as well as the connections between the annual runoff total control rate and drainage pipe design goals, and runoff pollution control objectives. Finally, this strategy was implemented in Ningbo's sponge city development.The research findings reveal that: ① This strategy enhances both the rationality and economic efficiency of the annual runoff total control rate indicator.② According to this approach, by setting the annual runoff total control rate in Ningbo City at 75%, maximum cost-effectiveness in sponge city development can be achieved under reasonable engineering conditions.These research findings can serve as valuable references for sponge city development in other Chinese cities.