Liquid metal X-ray diffractometer consists of three parts: X-ray collection system、vacuum and atmosphere protecting system、specimen heating and moving system、automation system. The X-ray diffraction was carried out adopting q-q type. Measurements were carried out in high purity helium atmosphere before the chamber was cleaned by vacuum equipment. Specimens were placed in an alumina crucible, and were heated by a pair of Ta sheets. Mo Ka radiation was reflected from the free surface of the liquid specimen, the X-ray then reached the detector through a graphite monochromator in the diffraction beam. During the measurements, the surface of the specimen was fixed to one horizontal position by means of a laser calibrator. The Diffraction X-ray scattering intensity measured in arbitrary units can be converted into the coherent scattering intensity per atom in an electron unit. Structure factors、pair correlation functions、coordination number、nearest neighbor distance and so on, can be obtained by calculation and analysis of experimental datum.