Building roof rainwater collecting and utilization and initial rainwater discard device

The invention relates to the technology of water resource high-efficiency utilization, in particular to the technology of rainwater resource utilization, and specifically discloses a building roof rainwater, rain energy collection and utilization and initial rainwater discard device, which comprises a water collecting slope, a water collecting plate, a water discard tank, a counterweight, a watercollecting tank, a water sieve plate, and a transit shaft; the water collecting plate is mounted on the top of the water collecting tank through the transit shaft, and the water collecting plate is rotatable around the transit shaft; the water discard tank and the counterweight are mounted at the bottom of the water collecting plate and distributed on both sides of the transit shaft correspondingly, the plate surface of the water collecting plate is a concave panel, the concave point communicates with the confluence port of the water discard tank, and the counterweight side of the water collecting box is provided with