Abstract: In order to measure and adjust the temperature and humidity accurately, natural cold source was used to improve control quality of fruit granary, and a control system of temperature and humidity in fruit granary was developed. The system can enhance the control effect of fruit storage. The temperature and humidity of fruit granary were controlled by using assemble language with the 8031 type singlechip microcomputer of series MCS-51. The error range of temperature was controlled in ±0.2℃, and the linearity of humidity was kept in range of 50%～100%. The process was displayed with figure code and printed.