Abstract: A practical approach to produce 50-60 keV quasi-monochromatic X-ray by selection metal filter was studied. The appropriate metal filter was selected after various types of filters were tested. The mechanical structure of the collimator was also determined. According to the experimental requirement, a X-ray machine was assembled with a X-ray tube, a collimator and an ultrahigh voltage power source. This device generates standard spectrum of quasi-monochromatic X-ray in the energy range of 50-60 keV, and the X-ray machine can present an appropriate substitution to ²⁴¹Am low energy photon source in the traditional level indicator.