Abstract: With the increasing frequency of flood disasters, the application of stormwater detention tank and LID measures is increasing. Take the rainwater pipe system in one area of a coastal city as an example., the SWMM model is used to simulate the rainwater system to increase the hydraulic status of the centralized or decentralized stormwater detention tank and the stormwater detention tank combined with the LID measures. The results show that the stormwater detention tank can directly play a role in reducing the design flow of the downstream pipe section, effectively improving the design return period of the regional drainage system; for the goal of comprehensively controlling the storm water torrent, small volume, decentralized multi-tone The reservoir mode is more effective than the large-volume, centralized monotonic storage mode; the LID + stormwater detention tank measures have a significant reduction in total runoff and runoff peaks and can effectively reduce the volume of the storage tank and reduce the land occupation.