Abstract: The coalescence processes of Cu-nanoclusters with different sizes and initial temperatures were studied by molecular dynamics simulation within the framework of embedded atomic potential. How the size/temperature effect of the nanoclusters changes in coalescence process was recorded by snapshots to calculate the geometry parameters of configuration of the system and reveal the temperature changes in the process. The simulation results showed that a nanoclusters coalesces with other ones to a greater degree and the temperature changes greater with the decreasing cluster size at constant initial temperature. However, for the clusters of same nanosize, they coalesce together to a greater degree with increasing initial temperature. Moreover, the nanoclusters in liquid state coalesce together much easier than those in solid state.