Abstract: The calibrating results of solar X-ray detector aboard on FY-2C are presented in this paper. The transducer of solar X-ray detector is proportional counter. The gas in the transducer is Ar. The solar X-ray detector can monitor the sun＇s X-ray flux above 4 keV in ten channels. The methods and results of experiments for calibrating are presented in detail. The radiation source used in these experiments are 241Am and 55Fe. The calibrating results are listed in six aspects： characteristics of plateau, efficiency, proportional characteristics, determining of energetic channels, energy resolution and time resolution. The plateau length is about 300 V. The plateau slope is less than 5%/100 V. The working voltage range of the detector is 1600-1900 V. The efficiency curve is calculated theoretically, and the material of the detector is taken into account. The experiments results show that the detector has good proportional characteristic. The time resolution of solar X-ray detector is 8.2 s. The solar X-ray detector aboard on GOES adopted ionization chamber, that is different from FY-2C. The detected results of solar X-ray detector aboard on FY-2C are compared with those of GOES. They fit well. The results show that the solar X-ray detector aboard on FY-2C works well to monitor the X-ray flux of the Sun and contribute much to the space environment monitoring.