The invention discloses a long-span orthohexagonal concrete honeycomb open-web sandwich floor covering and a manufacturing method. The covering comprises an upper chord layer and a lower chord layer. The lower chord layer is composed of a plurality of completely identical orthohexagonal grids formed by open web girders, with the three-way cross included angle being 120 degrees, in a crossed mode. The upper chord layer is composed of reinforced concrete prefabricated ribbed slabs with regular triangular grids, wherein the size of each regular triangular grid is one sixth that of each orthohexagonal grid, and regular triangular ribbed beams are formed below the regular triangular grids. According to the covering structure, the defect that according to traditional framed girders, beams and columns are too thick can be overcome, the orthohexagonal honeycomb grids formed by the open web girders with the three-way cross included angle being 120 degrees are selected, and spatial three-dimensional stress of the covering is guaranteed; the void fraction is high, the dead weight is low, and the construction cost is reduced by 20% or over compared with that of conventional structures; and in addition, the multi-storey long-span covering can have the exquisite grid appearance, and the construction policy that the covering is applicable, economical, environmentally friendly and attractive is met.