Combined type floor drain pipe hole reserving device and using method

The invention relates to the technical field of building construction, in particular to a combined type floor drain pipe hole reserving device which comprises a cross-shaped supporting frame and four sets of cylinder assemblies composed of 1/4 arc-shaped cylinders and cover plates, and the peripheries of the upper end faces of the 1/4 arc-shaped cylinders are rotationally connected with the lower surfaces of the cover plates through hinges; the section of the cover plate covers the shape defined by the section of the 1/4 arc-shaped barrel, a clamping ring is arranged on the cover plate, a clamping groove is fixedly formed in the inner wall of the 1/4 arc-shaped barrel, and the cross-shaped supporting frame is smaller than a notch of the clamping groove in overall dimension. The assembly has the advantages of being capable of being manufactured in a finalization mode, high in replaceability of all parts, convenient to construct, easy to dismantle and convenient to use in a turnover mode, guarantees constructio