Abstract: A stair tread structure includes a tread body made up of a core layer, a plurality of lateral connecting members, a tread end member, a plurality of external connecting sheets, and an elongate nose member wherein the core layer and the tread end member are respectively made up of one or more than one board bodies of recycled wood, plywood, sawdust, and other lower quality materials that are integrally processed and firmly bonded into one piece. The core layer has a pair of lateral coupling portions symmetrically protruding at both lateral end surfaces thereon, and the lateral connecting member is provided with a coupling groove indented at one lateral end surface to correspondingly match with the coupling portions of the core layer for close engagement therewith. Therefore, via the aforementioned structure thereof, the tread body obtained thereby is efficiently manufactured in an easier and speedier manner and economically processed with the best use of recycled resources for environmental protection thereof.