Abstract: According to the liquid separation property of Cu-base alloy,the Cu-base coating is obtained on the aluminum alloy by CO2 laser cladding for improving the surface strength of aluminum alloy.The results show that the matrix of the coating is Cu-base solid solution,and the main reinforcing phase is laves phase,which shows a dispersion distribution character.The reinforcing phase shows a composite structure of "Mo-rich core"+"surrounding phase".This is mainly caused by the separation of Mo-rich cores,which furnish the liquid separation with heterogeneity nucleation surface.The microhardness test shows that the microhardness of the coating is about 270HV0.05,two times higher than that of the substrate ZL104 aluminum alloy.