Sintering process of copper atom clusters is investigated by multi-resolution molecular dynamics (MRMD) simulation. This MRMD method is constructed as combination between calculation of atomic motion in boundary regions being done by ordinary MD method and calculation of rigid body motion of clusters being done by another kind of equation. Two dimensional array of 683 copper atom-clusters is studied, and it is found that adequate reappearance of the behavior about translation, collision, coalescence, and oscillation of clusters is capable to be obtained by MRMD method with new algorithm in determination of MD region.