Abstract: Multi-walled carbon nanotubes reinforced aluminum matrix composites was prepared by laser casting.Transmission electron microscopy,scanning electron microscopy and X-ray diffraction have been carried out to observe and analyze the forming quality and interfacial bonding behavior between carbon nanotubes and aluminum matrix.The results show that multi-welled carbon nanotubes reinforced aluminum matrix composites can fuse without the damage of carbon nanotubes structure when the laser energy input was 800×10⁵J/m².The matrix alloying element Mg can decrease the surface energy of matrix,and improve the wettability and interfacial bonding between carbon nanotubes and aluminum matrix.With the addition of 3 wt% Mg and 5 wt% carbon nanotubes,the casting quality of composites was enhanced.In the composites crack profile,pull-out carbon nanotubes from aluminum matrix were observed.