Rainwater recycling device suitable for viaduct

The rainwater recycling device comprises a rainwater falling pipe, a water collecting unit, a water supply unit, a greening unit and a water drainage unit, and the upper end of the rainwater falling pipe is communicated with a viaduct deck; the water collecting unit comprises a flow discarding box and a water storage box, the lower end of the rain down pipe is communicated with the flow discarding box, the water storage box is communicated with the flow discarding box, and the flow discarding box is communicated with a municipal sewage system; the water supply unit comprises a first water outlet pipe and a second water outlet pipe, the first water outlet pipe is communicated with the water storage tank, and the second water outlet pipe is communicated with the water storage tank; the greening unit comprises planting soil which is used for planting plants; the drainage unit comprises a third water outlet pipe which is communicated with a municipal sewage system. When the rainfall is large, water in the water s