Abstract: The automatic measuring system of temperature and moisture in grain depots was developed by using MCS-51 series microcontrollers, and its working principle and design methods were also introduced in the paper. In the system, the scores of sensor of temperature were made of thermistors with high sensitivity and low price, and these sensors overcame the shortcoming of bad linearity and steadiness by using software. After calculating and data processing, detecting of moisture is changed to measuring of temperature. Thus the circuit became simplified and production costs were reduced. Reliable working has become true because a series of software anti-interference measures were taken in the system.