Abstract: CO₂ laser welding process of AZ31 magnesium alloys with filler wire was investigated using a special CO₂ laser welding experimental system.The effect of welding parameters was systematically researched using AZ31 wire as filler materials and a suitable parameters range was obtained.The properties of two typical welds were studied after welding experiment.The results show that, when the filler metal of AZ31 was used, the weld appearance is good and the disadvantage of obvious concave top surface for normal laser welding (no filler materials)can be overcome.The analysis results indicate that the microstructure of weld zone is consisted of small dendritic grains.The microhardness and tensile strength of two typical joints are almost the same as those of the base metal, which implies that the welds formed with filler wire have good mechanical properties.Laser welding with filler wire provides a good method to realize the welding of AZ31 magnesium alloys.