Abstract: In view of the characteristics of flash flood entering the city and flood in coastal polder area, this paper explores a new idea of flash flood control and flood coordination in the city. Taking Yelin Road area in Zhuhai as an example, a flood prevention system model was established using InfoWorks ICM to scientifically evaluate the regulation and control effect of flash flood storage and drainage. Based on the causes of flash flood causing waterlogging, this paper puts forward the countremeasure idea of "one storage, two smoothing and three interception" of flash flood in coastal cities. Taking into account the principle of flood and waterlogging simultaneous control, the paper puts forward a systematic control idea of "upper storage-middle connection-lower drainage", and makes overall plans for the storage and detention of mountain torrents in the upper reaches, the smooth connection of passageways for flood discharge and the balance of storage and drainage in the lower reaches, so as to carry out the change from fragmentation to systematization of flood and waterlogging control. Through the model verification, it is found that the flood peak discharge can be reduced by 47%, the flood risk in urban built-up area can be reduced. After the downstream discharge channel is widened and the forced drainage pump station is installed, the Yelin Road area can effectively deal with the rainfall with a return period of 50 years and ensure the safety of the city.