The mezzanine floor structure is a knock-down type, suitable for industrial factories and warehouses, to increase usable space in the air with a sturdy steel structure. It can support weights of 300 – 1,000 kilograms per square meter. It is easy to assemble and install, and can be extended, dismantled, or modified for relocation to other areas conveniently. It is suitable for increasing usable space in buildings, factories, warehouses, etc.