The molecular-dynamics (MD) simulation based on the tight-bind potential for a liquid Al5Fe2 has beencarried out to invstigate the structure of medium-range order (MRO), combined with X-ray diffraction experiment. It is found that there exists an obvious prepeak in the low-Q domain (Q=15.7 nm^-^1) of the structure factor. In the X-diffraction pattern, the liquid diffraction curve is corresponding with the solid diffraction curve. There exist the prepeaks for them in the low-Q domain, which shows that there is the comparability in the microstructure between them. Both the chemical order parameter and the Bhatis-Thornton (BT) partial structure factors indicate the existence of stronger chemical-range order (CRO) in the liquid alloy. The maximum and minimum in SFe-Fe(Q) and SAl-Fe (Q) at Q=15.7 nm^-^1 also show the existence of superstructure. We have also calculated the neighbor numbers of the system and given the structure model representing MRO.

Key words: IRON ALLOYS, ALUMINIUM ALLOYS, FUSE ELEMENTS, MICRO- STRUCTURE, MOLECULAR DYNAMICS, X-RAY DIFFRACTION ANALYSIS