Through analyzing the factors that can effect the stability of the temperature and humidity of the humid air during the wood drying process,the types of the temperature and humidity controller(THC)and the different controlling manner of THC,conclusion was made that:in conventional drying kiln,it was an economic and practical choice to use the dry bulbwet bulb intelligent \{instrument\} of temperature and some circuit,which could meet the needs of wood drying in semiautomatic system.The characteristics of autocontrol system were analyzed and the advice to improve the system was provided.