Roof rainwater collecting, purifying and recycling system

The utility model relates to a roof rainwater collecting, purifying and recycling system. Due to rapid development of urbanization and continuous increase of population, urban water consumption is increased, and water resource supply shortage is caused. The rainwater collection system comprises a plurality of rainwater collection tanks arranged on a roof, the rainwater collection tanks are communicated with rainwater downpipes, the rainwater downpipes are connected with a water storage tank, the water storage tank is connected with a municipal rainwater pipe, the water storage tank is furtherconnected with a residential building recycling pipeline, and a water pump is arranged on the residential building recycling pipeline. An anti-backflow valve is further arranged at the inlet end of the municipal rainwater pipe, an iron gauze is arranged in the rainwater down pipe, pebbles with degrading bacteria are further arranged on the rear portion of the iron gauze, and a plurality of sewagefiltering layers are arran