The granary temperature and humidity measuring system, realization P89V51RD2 single chip as the main control core, and a RS232 bus communication mode of granary temperature and humidity monitoring system. Host by P89V51RD2 master MCU driving, and display temperature, humidity, and Luminance, entering commands by keyboard. Attached master machine used 51 core chip STC12C2052AD, digital temperature and humidity sensor SHT10 is used for data acquisition, master and attached master machine all use of serial communication. When the temperature and humidity calibration value is exceeded, it will alarm at the same time.