The invention discloses a laser double-beam welding device and method. The laser double-beam welding device comprises a beam splitter and a laser scanning device. The beam splitter is used for splitting an initial laser beam transmitted to the beam splitter into a first beam and a second beam, wherein the first beam is used for acting on welding flux. The laser scanning device is used for scanning the input second beam into a swinging light beam, wherein the swinging light beam is emitted in the direction roughly parallel to the spreading direction of the first beam and swings in the preset swinging direction in the emitting direction, and the swinging beam is used for acting on an area to be welded. According to the laser double-beam welding device and method, the problem that the area to be welded is not fused can be effectively solved, the welding quality is improved, and the stability in the welding process can be guaranteed as well. Meanwhile, repeatability in the welding process can be improved, and the welding efficiency can be better improved.