The invention discloses a rain and flood utilization system, which integrates project measures and ecological environment, is widely applied to the technical field of rain water utilization and particularly relates to the rain and flood utilization system in building zones. The whole process of the rain and flood utilization system is completed through rain water converging, safe diversion, abandoned flow control, filtration, storage, water quality keeping, purifying treatment and comprehensive utilization. The system has a security function of automatic alarm, avoids blockage and siltation, ensures smooth filtration, reduces potential safety hazard, realizes quaternity integrated recycle treatment, namely sterilization, activation, filtration and oxygenation, of stored water, further guarantees the water quality, prevents secondary pollution of an impounding reservoir, reduces load of water quality treatment and saves investment and operation cost.