Abstract: The composition, structure and properties of Cu-W thin films fabricated by magnetron sputtering were characterized by EDX, XRD, TEM, SEM, resistance meter and microhardness instrument. The effect of W atom fraction was discussed. The results show that Cu-W thin films with 31.8 at%-54.8 at% W were amorphous and had smooth surface. Thin films with 18 at% W and 60 at% W were crystalline state with solid solubility expansion in the fcc Cu(W) metastable supersaturated solid solution and bcc W(Cu) solid solution, respectively. The electrical resistivity of Cu-W thin films was higher than that of pure Cu films, and the resistivity of amorphous Cu-W thin films was over 1.9 times higher than that of crystalline films. The microhardness of Cu-W thin films was correlated positively with W content, the hardness of amorphous and crystalline Cu-W thin films was lower and slightly higher than the calculated values by Voigt fomula, respectively.