Abstract: Normal flat-sawn samples (7mm. in grain, 40mm. in tangential, 40mm. in radial) of four species, i. e., Pinus massoniana (soft wood), Fraxinus mandshurica (ring-porous wood), Juglans mandshurica (semi-diffuse porous wood), and Acer mono (diffuse-porous wood) were used and dried at 100, 80, 60 and 40C respectively. Comparisons were made between the water-saturated samples and the semi-dried ones, between samples steamed for 1 hour before drying and those that had not been steamed and between the ab ;orption of moisture at the drying temperature and that at the artificial moist climate after drying, and regularities of the variability of swelling and shrinkage of wood resulting from the difference of temperature, steaming treatment, moisture content, and species have been found out. In addition, delaying phenomena were observed when the dimensions were varying from swelling to shrinkage or vice versa. This paper maintains that the definition of dry check potential is applicable to the drying technique. Based on the test results, questions about the fibre-saturated-point and the stresses during driyng are also discussed,