Abstract: This paper presents the influence of laser-TIG welding mode, distance between the laser and arc(DLA), laser pulse parameter on the formation of magnesium alloy T-joint. Results show that the TIG-laser hybrid mode is benefit for the weld formation. In TIG-laser mode, greater welding penetration depth can be obtained when the D_la increases with the increase of arc current. Good T-joint formation was gained at 100 A arc current and 3 mm D_la. An extremely large or small laser pulse width deteriorates the weld root formation. When the laser pulse width is extremely small, the junction of the wall panel and strengthening rib will be over-heated, resulting in the surface collapse or even burnt-through. When the laser pulse width is too large, the wall panel and the strengthening rib cannot melt and effectively joined together.