The utility model discloses a novel roof building water conservation structure, including the main part building, be provided with the reservoir bed on the roof of main part building, be down " V " font between reservoir bed and the roof plane, each border each wall limit of follow main part building of reservoir bed is stretched out and is the eave form, the border department that the reservoir bed height is minimum is provided with the delivery port, be provided with two water receiving pipes that the structure is the same on the roof of main part building downwards, the butt joint is managed with the water receiving under the delivery port to the delivery port, the tank connection of water receiving pipe bottom the main part building, the upside of each border department of reservoir bed all is provided with closed waterwall, be provided with the wash port on the waterwall, the upper portion slope of reservoir bed is provided with the division board, the wash port is located the topof division board and is close to the low side of division board. The utility model discloses structural design is novel, simple and practical moreover, and the rainwater that can solve present building roof directly emits into the downcomer, and the water resource does not obtain the technical problem of rational utilization.