Cu films were deposited on Si and K9 glass substrates by magnetron sputtering technique. The influences of varying thicknesses and substrates on the transient reflectivity of Cu films were studied by using femtosecond laser pump-probe technology. The results show that the transient reflectivity curve of Cu films in different thicknesses have the same trend except that when they reach the peak value and recover to the balance. When the laser power is 40 mW, the influence of Si and K9 substrates on the transient reflectivity curve of 20 nm Cu films is relatively small. But when the laser power is160 mW, the influence of Si and K9 substrates on the transient reflectivity curve of 20 nm Cu films have obvious difference, the former needs much less time to reach the thermal equilibrium than of the later. At the same time, the influence of different substrates on the transient reflectivity curve of 200 nm Cu is also small.