Welding tool for liquid cooling plate and laser welding method

The invention discloses a welding tool for a liquid cooling plate and a laser welding method. The laser welding method comprises the following specific steps of firstly, putting a water nozzle of the liquid cooling plate into a clearance hole of a lower welding plate, then putting a flat plate into the welding tool for positioning, enabling a hole of the flat plate and the water nozzle to be nested and butted to form a splicing weld joint, and carrying out sealing welding through laser welding; secondly, placing a stamping runner plate on the flat plate where the water nozzle is welded, positioning, tightly pressing an upper plate of the welding tool and the stamping runner plate to be tightly attached, and keeping a gap to be smaller than 0.1 mm; and thirdly, after the liquid cooling plate is placed, using welding laser for conducting penetrating stitch welding on the welding area of the liquid cooling plate through a preset hollowed-out position of the welding tool, and finally dismantling the welding tool