The author gained a good deal of enlightenment from the industrial production and scientific research development of wood drying that has been underway both at home and abroad, the idea is formed of wood drying under floating pressures, i. e., forcing the energy to enter rapidly the interior of wood by means of increasing pressure at rising temperature; introducing medium pressure as the major parameter to be controlled-the very fourth essential factor of wood drying; creatingthe initial condition and marginal condition in favour of moving water from the interior to the surface layer 5 accelerating the drying procedure at a limited gradient of moisture content. A series of experiments in the light of the idea mentioned above show drying under floating pressures is a practical method. It has been qualitatively brought about a drying equation under floating pressures, i. e.,Ultramicrostructure analysis is also involved here. Somenew tentative ideas are put forward of the subjects to be further studied.