Abstract:It is found that the internal temperature of the lumber dried by electric heat far infrarea radiation may be higher than the external temperature. The primary analysis is made. Under a particular condition, the rate at which the lumber reaches higher temperature internally than externally depends on its moiscure content (m. c.) and thickness. If the lumber is thick and contains more m. c. , the rate is slow and fast reversely. The rate also varies with lumber‘s internal structure, the dense wood is slow, and the loose one fast. The temperature between the internal and external wood is different based on the m. c. and thickness of lumber. The thinner the lumber and lower the m. c. , the smaller the temperature difference. Temperature of wet ball is more important in drying.To dry the medium-thick block the temperature is 50-65℃; to thick block, 60-75℃; and to very large square lumber, 70-85℃.