The invention discloses a blast furnace shell and water-cooled furnace bottom cross construction method and belongs to the field of blast furnace overhaul. The construction method comprises the stepsthat after a blast furnace shell is dismantled, a layered platform is arranged on a tuyere platform; when a water-cooled furnace bottom is constructed below the layered platform, the portion, below atuyere zone, of the furnace shell is assembled on the layered platform; the portion, below the tuyere zone, of the furnace shell is aligned in place immediately after a furnace bottom closure plate and a blast furnace shell bottom plate are arranged in place, and the layered platform is restored again; the tuyere zone and the portion, above the tuyere zone, of the furnace shell are assembled on the platform, and the cross joints between the furnace bottom closure plate, the blast furnace shell bottom plate and a first-zone furnace shell and a reinforcing rib plate between the bottom plate andthe first-zone furnace shell can be welded below the platform; after completion of welding, the elevation of the topmost ring of the installed furnace shell is checked; if the elevation of the topmostring of the installed furnace shell meets the requirement, the layered platform is dismantled, and the tuyere zone and the portion, above the tuyere zone, of the furnace shell are installed. By applying the blast furnace shell and water-cooled furnace bottom cross construction method, the construction period of a constructed main line can be effectively shortened. The blast furnace shell and water-cooled furnace bottom cross construction method has good economic benefits and social benefits, can be used for overhaul of various type of blast furnaces and is high in practicality.