Building fire water supply device for collecting water

The building fire-fighting water supply device comprises a water collecting tank, a rain hopper and a fire-fighting pipe, the fire-fighting pipe is communicated with the water collecting tank, and the rain hopper is connected to the upper end of the water collecting tank through bolts and used for collecting rainwater into the water collecting tank; a sealing plate is further arranged above the rain hopper, and the rain hopper is connected with the sealing plate through a hinge shaft seat; and an ice crushing device is arranged in the water collecting tank. By arranging a solar panel, the equipment is subjected to electric power storage in the solar panel in the daytime, the solar panel transmits an electric signal to a heat conduction pipe and a motor in the inner-layer pool wall, and internal water is subjected to heat preservation treatment so as to be prevented from being frozen in winter; an inner ice crushing device is started to crush massive ice, and the ice is uniformly heated and melted into water w