Abstract: The effect of welding parameters including laser power,welding speed and shielding gas flow rate on the laser welding process of magnesium alloys were researched.It was indicated that the weld widths at top and back side are both increased when the laser power is higher.And the weld width decrease with welding speed being increased.AZ61 magnesium alloys had a higher molten efficiency than AZ31 under the same welding parameters and a larger weld width is obtained for AZ61.The top and back shielding gas flow rate have few effect on the weld width.However,they directly determine the shielding effect of weld surface.The welding of AZ61 and AZ31 magnesium alloy sheets with different thickness can be successfully carried out by using CO₂ laser welding method under the proper process conditions.Moreover,the formed weld has ideal appearance and good mechanical properties.