At present, common laser welding techniques, including pure laser welding, laser wire filling (Q345GNHL weather resistant plate) welding, and laser arc composite welding, are also the main welding techniques for power laser welding. In pure laser welding, due to the lack of filler metal, there are high requirements for the joint gap of the welded parts, requiring small gaps and avoiding large misalignment. Therefore, pure laser welding is generally less commonly used in single pass laser butt welding of thick plates to avoid excessive surface indentation of the weld seam. Laser wire filling welding has a certain tolerance for gaps due to the addition of filler metal. Laser arc composite welding, generally referring to laser melting electrode arc composite welding, further improves the gap tolerance due to the melting efficiency of the melting electrode. At the same time, the addition of arc heat source enriches the changes in thermal cycling during the welding process.