A welding system comprises a welding module and a moving module adapted to move the welding module to a predetermined welding position. The welding module includes a guiding device and a welding tool. The guiding device has a plurality of tubular guiding heads arranged in a row, ends of the plurality of tubular guiding heads are disposed close to joints of a plurality of cables so as to guide a plurality of welding wires to the joints of the plurality of cables. The welding tool has a plurality of tooth-shaped welding heads arranged in a row, ends of the plurality of tooth-shaped welding heads are disposed close to the joints of the plurality of cables and configured to simultaneously heat the plurality of welding wires guided to the joints of the plurality of cables, so as to simultaneously weld the joints of the plurality of cables onto a circuit board.