The 6061-T6 aluminium alloys are welded by the laser-TIG hybrid heat source at a high speed. The influences of process parameters such as arc current, laser pulse duration and laser frequency on pore formation are studied. The results show that, in the process of laser-TIG hybrid welding of 6061-T6 aluminum alloys at a high speed, the increase of welding speed makes the cooling speed of molten pool increase, there exist thin isometric crystals in the weld microstructure, and the width of softening zone in the heat affected zone decreases. The change of the cooling state of the molten pool results in the reduction of keyhole stability, the easy collapse of keyholes, and the easy formation of pores in welds. With the increase of laser pulse duration, the number of pores decreases, and the diameter also decreases. With the increase of laser pulse frequency, the number of pores first decreases and then increases. When the arc current increases from 180 A to 200 A, the number of pores in welds significantly reduces.