Abstract: Many studies in quantum technology need to be carried out at ultra-low temperature(< 1 K).The measure-ment temperature is a basic part in these experiments.Thermometers for ultra-low temperature must be calibrated before they are used.However, the thermometers for ultra-low temperature and their calibration service are almost monopolized by a few foreign companies.This makes the use of these calibrated thermometers extremely expensive.This is very disad-vantageous to these experiments below 1K.In order to change this situation, a thermometer calibration platform was built on self-developed Adiabatic Demagnetization Refrigerator(ADR) cryostat.On this platform, a batch of homemade ruthe-nium oxide thermometers were calibrated in the temperature range of 770 mK to 6.7 K.The R-T curves are basically coin-cident.We can see a consistency in this batch of ruthenium oxide thermometers from the results.The results show that the calibration platform is capable to calibrate thermometers below 1 K.