Through the high temperature X-ray diffraction, structural evolution of Ag 70 Au 30 alloy with varying temperatures has been investigated. The liquid alloy experiences a sudden structure change nearby 1150 °C, which has been further thermodynamically confirmed by Differential Scanning Calorimetry (DSC). Small pre-peaks have been found in the structure factor (S(Q)) curves, indicating the stable medium-range order (MRO) structure in the melt. As the temperature decreases from 1100 °C to 1000 °C, MRO structure gets more pronounced. Compared with the structures of Ag 90 Au 10 , Transmission Electron Microscope (TEM) results reveal that Ag 70 Au 30 alloy possesses much finer grains. It is concluded that there are strong correlations between melt and solid in Ag 70 Au 30 alloy, and MRO structure in the liquid favors refined solid microstructure.