Recently, a lot of work, both experimental and theoretical, is focused on nano-clusters formed by evaporation, ionic spray methods and so on [1–6], however, the other kind of nano-clusters, formed in liquid metallic systems during solidification processes, is still neglected up to now. It is well known that for investigating the formation characteristics of nanoclusters during solidification processes of liquid metals, it is necessary to trace the transition processes of microstructural configurations in the system step by step. Under present experimental conditions, it is difficult to complete such a tracking research. Fortunately, due to the rapid development of computer technique, the molecular dynamics method has been used to make such a tracking study, and some very clear physical pictures of the instantaneous processes of microstructure in a small liquid metal system consisting of 500 Al atoms have been obtained in the past years [7–12]. However, in the small system, it is still difficult to research the clusters, especially the nano-clusters. In this paper, based on the author’s works [10–12], a large-scale liquid system consisting of 400 000 Al atoms has been used to perform a simulation study on the formation process of nano-clusters during rapid solidification by using constant-pressure molecular dynamics method and parallel algorithm on the Clare supercomputer. The conditions for simulation calculation are as follows: at first, the 400 000 Al atoms are placed in a cubic box and their calculation task is distributed into 40 machines, and then the system runs under periodic boundary condition. The interatomic potential adopted here is the effective pair potential function of the generalized energy independent non-local model–pseudopotential theory developed by Wang et al. [13, 14], and the function is