Taking 3 mm thick 6082-T6 aluminum alloy as the base material for laser-MIG composite welding, this paper investigates the influence of laser power and wire feed speed on the weld forming, microstructure and mechanical properties, and the porosity defect of welded joints under different power was analyzed. Results show that the weld seam forming was the the best with the laser power of 1 900 W, wire feed speed of 4 m/min, and the microhardness of the joint from the base material to the center of the weld shows a trend of first decreasing and then increasing. Moreover, the heat affected zone exists the phenomenon of softening, and tensile strength and elongation reach up to 313 MPa and 6.18%, respectively. The center of the weld is organized as fine equiaxed grains, and the fusion zone is composed of columnar crystal growing perpendicular to the fusion line. In addition, the number, size and porosity of the joint pores increased with the increasing of laser power.