Monochromatic X-rays calibration facility is a device that generates monochromatic X-rays based on Bragg diffraction. The continuous adjustable monochromatic X-rays can provide detailed calibration experiments with optional energy for a detector. Monte Carlo calculation software is used to simulate the detection efficiency of two different types of silicon drift detectors, and the detection efficiency of the 3 ~ 50 keV energy band is obtained. The calibration experiment of the detection efficiency of the SDDs is completed on the monochromatic X-rays calibration facility, and the detection efficiency measured by the experiment is obtained and compared with the simulation efficiency. Moreover, the maximum error between the experimental results and the theoretical calculation results of MLC SDD is 4. 23%@ 15keV, and the maximum error between the experimental results and the theoretical calculation results of BEV 133 SDD is -6. 88%@ 12keV. The results show that the experimental calibration of the two detectors are consistent with the theoretical calculation results in the energy band of 7~ 16 keV, and the real detection efficiency is greater than 90% at 8 keV. The research results verify the superiority of using Bragg diffraction-based monochromatic X-rays for detector calibration, and also provide a reliable performance research and testing platform for domestic X-ray detectors.