Abstract: A series of molecular dynamics simulations for the structure transformation of liquid Cu during isothermal solidification were performed with the Tight-binding potential. Static structural information on the pair distribution functions and the coordination number distribution at different temperatures were obtained while an analysis was carried out on the possible change of short-range ordered structure of FCC crystal and its resultant types of atom pairs by means of the Honeycutt-Anderesen pair analysis technique. The results indicate that the 1551 bonds change into the 1541 bonds during solidification process and the formation of initial three-dimensional structure depends mainly on the diffusion and relaxation of Cu atoms in two directions.