Abstract: A raised floor supporting structure including a plurality of upright supports, a plurality of top stretchers and bottom stretchers respectively connected between the upright supports at different elevations, wherein each upright support is comprised of a circular base having an upright socket and radial reinforcing ribs extended from the upright socket, a reinforced upright tube mounted in the upright socket of the circular base and covered with a top cap, a screw member inserted through the center hole of the top cap into the upright tube, a nut threaded onto the screw member and supported on the top cap and turned to adjust the elevation of the screw member, a bracket mounted on the screw member at the top for holding floor panels; each top stretcher has a coupling portion at each end respectively coupled to a respective coupling portion of the bracket of one upright support, and a pin hole at each end respectively coupled to a respective upright pin of the bracket of the corresponding upright support; each