Freezing processes of liquid Cu nanoclusters with atoms of 147，309 and 561 are performed by means of molecular dynamics，which show that the structures of the obtained solid nanoclusters at room temperature are governed by the cooling rate and the clusters' sizes: the smaller clusters and the slower cooling rate bring the icosahedra structures more favorably, and contrarily， for the larger clust ers and the faster cooling rate，the face centered cubic structures will be expe cted in our simulation time. The physical mechanisms of this phenomenon are also discussed in this paper.