In China, there is considerable proportion of forests from which only small timber is available, most of them are hardwoods, With pith, larger crook, knot and other growth nature, the timber is subject to crack and difficult to be dried, this fact brings problem to drying process as well as following processes. Based on the experiments and industrial tests on oak, birch and some other species, it is found that high medium temperature treatment is not suitable for the small hardwood drying. The timber may be properly treated under lower intensity of water vaporisation with middle or low medium temperature and the variance of temperature in the direction of thickness of timber should be kept stable.