Abstract: Laser beam welding was conducted on SiC particle reinforced LD2 Al alloy matrix(SiC_p/LD₂)composite and the microstructure of weld was investigated by means of optical microscope, X-ray diffraction and electronic probe micro-analysis.The result showed that within the range of heat input, interface reaction took place in all the welds, and acicular Al₄C₃ was formed. Both the size and quantity of acicular Al₄C₃ increased with energy input, and the shape of gas pore changed from circular to angular. With a sheet inserted between the composite workpieces, formation of Al₄C₃ was effectively suppressed and joints with fairly high strength were obtained.