The invention relates to a thermistor and belongs to the field of thermistor detection. A high-precision thermistor thermometer calibrating device comprises a high-precision thermistor thermometer to be calibrated, an etalon, a temperature-measuring bridge, and a thermostatic bath and is characterized in that the high-precision thermistor thermometer to be calibrated and the etalon are placed in the thermostatic bath and are connected to the temperature-measuring bridge; the temperature-measuring bridge measures two sets of temperature data and sends to a data fitting system the temperature data to be fitted for calibrating the high-precision thermistor thermometer to be calibrated; the etalon is a standard platinum resistance thermometer; the data fitting system comprises a data importing module, a data fitting module, and a fitting result and error precision calculating and analyzing module; the data fitting module comprises a data fitting algorithm selection submodule connected with a corresponding algorithm submodule. The data nonlinear fitting method of the high-precision thermistor thermometer calibrating device is determined and a fitting result can be verified.