[Objective] Under the background of sponge city construction, building estates were studied to explore the control and utilization of the layout of a storage pool for rainwater runoff. The purpose was to provide technical guidance for the reconstruction of the old city sponge in the plain river network area, enhance the drainage and waterlogging prevention capacity, and improve the efficiency of rainwater utilization.[Methods] Taking the typical old estate of the Yanboyuan sponge reconstruction project in Jiaxing City as a case, a mathematical model of the drainage system was established based on storm water management model software. The optimal control water node was calculated by analyzing the relationship between the different rainfall recurrence periods and the water accumulation node in the study area. On this basis, the design rainwater control conditions were inputted, and the reasonable layout of the storage pool was explored.[Results] ① During the 5-15 years recurrence period, the distribution of the number of ponding nodes in the study area appeared to be in a stable period, and it reached the optimal level in the 9 years recurrence period. ② The ratio of the simulated volume to the storage pool between 20 and 100 m³ was 84%, and it had practical construction value. ③ After the suitable "low impact development plus storage pool" scheme was adopted, the effect of runoff control in the study area was evidently improved. The runoff peak reduction rate was more than 40%, and the coefficient of outflow runoff decreased by approximately 0.2. The miscellaneous water supply ratio was as much as 146.3%.[Conclusion] In the old urban areas in sponge transformation construction, we should pay attention to the rational layout and utilization of the storage pool to construct the runoff control system, combined with gray infrastructure and forestation, to attain efficient rainwater management.