Structural change of a molten Cu55 cluster on Cu（010） substrate during freezing at two different cooling rates is investigated by molecular dynamics simulations based on the embedded atom method. The analyses of energy per atom and pair distribution functions show that cooling processes have great influence on the structural changes. A rapid cooling rate results in the lower energy of the atoms in the cluster. At a slow cooling rate， the cluster atoms in the substrate are more likely to move to the substrate surface at high temperature， and then they form face-centred cubic configuration.