The single and unified design rainfall and its control rate indicator are conventionally adopted in the construction and effectiveness evaluation of sponge city in China, which makes it difficult to effectively guide and evaluate the construction of different LID facilities on the underlying surface. In view of this problem, we analyzed the spatio temporal heterogeneity characteristics of daily rainfall, design rainfall and its control rate, and discussed the quantitative influence of the current underlying surface storage and pipe network drainage on the control rate indicator in Nanning urban area using ArcGIS spatial interpolation, design rainfall and control rate relationship method and volume method, based on Quick Bird land use, the fine division of sub basins in 2020 and the Nanning 0.1° CMFD grid daily rainfall series from 1981 to 2010. The results show that the daily rainfall frequency, annual distribution, design rainfall and its control rate of Nanning urban area all showed significant spatial and temporal heterogeneity. The variation range of design rainfall of each month corresponding to 75% control rate was 9.72 (February)-32.05 mm/24h (July); however, the current annual total rainfall control rate of Nanning main urban area (area ratio:31.99%) is generally less than 50%, and it is difficult to achieve the target of 75% control rate only by the contribution of green LID facilities. To obtain the 75% control rate, it is suggested that the storage capacity of the main urban area should be in the range of 120-211 m3/hm2; however, the required storage capacity can be reduced to 30-108 m3/hm2 if the drainage capacity of the pipeline network reaches 70-103 m3/hm2. In conclusion, in order to achieve the target of 75% control rate of Nanning City, the quantitative function relationship of different control rate targets considering the temporal and spatial differentiation, storage capacity and drainage of pipe network should be established according to the current underlying surface level, which is a main way to effectively improve the rainfall runoff control capacity of sponge city.