Aluminium alloy is used widely in our society, but it is not good enough for many applications because it is soft. In order to harden the surface of the aluminium alloy, the surface is compounded by laser in this experiment. Here, two kinds of SiC power ,the diameters of which are nanometer-grade and micron-grade respectively , are compounded to the surface with Nd∶YAG pulsed laser separately. The experiment results show that