Abstract: Based on G-M refrigerator design to build a set of low temperature thermometer calibration system,the calibration system with temperature controller and PLC programming to realize the automatic control temperature records,data processing and data output calibration process of the integration. On the basis of imported silicon semiconductor thermometer calibration completed thermometer,by using the method of comparative index of p-n junction thermometer calibration,obtained the temperature characteristic curve and the error analysis. It is found that the system can not only achieve high calibration accuracy in the low temperature range of 4.2~100 K,but also shorten the calibration time and improve the effciency of the original calibration techonlogy due to the automation of the system.