Laser welding of 5083 aluminum alloys with high power CO₂ laser is experimental studied in this paper. The influence of laser power, welding speed and the focus position to the laser welding process as well as the assist gas to the instability of the welding process are analyzed. The experiment result shows that, under the precondition of the enough power density to striking, the reducing of the heat input and the using of the mix assist gas will achieve the stable and fine welding effect.