[Purposes] The annual runoff pollutant control rate is the core control index in the construction of sponge city, which is of great significance for guiding the design of sponge facilities. However, there is a problem that the calculation method and formulas in the design and calculation process are not uniform or unreasonable, and it is necessary to explore the calculation formulas that are more suitable for the practical projects. [Methods] The sources and calculation methods of the pollutant removal rate by sponge facilities in China and abroad were sorted out, and the problems existing in the calculation method of the pollutant removal rate and the average pollutant removal rate of land plots by a single sponge facility in the current engineering design were analyzed. Through the comparison of rainwater management runoff control indicators in different regions, the calculation method more suitable for the small-scale watershed of buildings and residential areas was deduced from the perspective of definition. [Findings] In the design of small-scale watersheds such as buildings and residential areas, it is more reasonable to use the weighted average of the effective catchment area of sponge facilities for calculation compared with the other three calculation methods of the average removal rate of suspended solids in the land plots by sponge facilities. In the calculation of the annual runoff pollutant control rate, it would be more reasonable to calculate it as the product of the average annual runoff pollutant control rate and the average pollutant removal rate by introducing the ratio of cumulative pollutant load rate to cumulative runoff volume rate. [Conclusions] Experiments or simulations should be actively conducted to calculate the annual runoff pollutant control rate, so as to form a database suitable for the actual situation in China. It is necessary to improve the designer’s understanding of the pollutant removal process from the source of sponge facilities and avoid the errors caused by the use of inappropriate formulas in the design and calculation of small-scale watersheds such as buildings and residential areas.