On the 3B3 medium energy X-ray beamline, a new monochromatic X-ray source tunable in the 2—6 keV energy range bas been constructed and implemented. The characteristic parameters of the X-ray source having been determined, with the help of the light source, we have calibrated the sensitivity of X-ray detector,thickness of filter,diffraction efficiency of crystals and energy response of the BAS5000-RS, which showed the high performance of the monochromator and detecter system.