Abstract: The Cu thin films were deposited on P-Si（100） substrates by magnetron sputtering at room temperat-ure.The surface morphology,nucleation and growth of Cu thin films on silicon were studied by growing a series of samples with different predetermined deposited times,which was followed by observation with atomic force microsco-pe（AFM）.The nucleation density of Cu grew on silicon with the increase of sputtering time.In the process of deposition,nuclei grew into islands,finally formed continuous films.When the sputtering time become to 15 s,there is a strange phenomena was observed.