A sawn wood drying system, which allows to take advantage of the heat contained in the dry wood that leaves the system to preheat the wet and cold wood that enters the system, the system comprising: a heating chamber, a drying chamber and a cooling chamber, sequentially arranged, and a transport path that allows the transfer of sawn wood through these three chambers; a first air circulation system, which provides a first high temperature air flow inside the drying chamber; and a second air circulation system that provides a second air flow, independent of the first air flow, which allows the heating chamber to be in fluid communication with the cooling chamber by means of external chambers or ducts connecting both chambers.