Rain-collecting, auto-flushing and flow-discarding device for roof

The utility model provides an automatic flushing flow abandoning device of roof rainfall collection, which relates to a rainwater preprocessing device in a roof rainfall collecting system. The rainwater preprocessing device comprises a water receiving groove and a rainspout, wherein the lower portion of the rainspout is further provided with an enclosed abandoned water pool, the bottom of the abandoned water pool is provided with an abandoned water pipe which is provided with a valve, a triplet is arranged between the rainspout and the abandoned water pool, the horizontal end of the triplet is vertically inserted in the abandoned water pool, and the vertical end of the triplet is extended in a ground filter chamber. The automatic flushing flow abandoning device can achieve the automatic washing and flow abandoning on of the roof rainfall collection system in initial rainfall of a roof, effectively lightens the labor intensity of users, improves the convenience of employment, and improves the water quality of the collected rainwater.