Oscillating laser welding provides an effective technical method for welding aluminum alloy sheets due to its outstanding role in suppressing pore defects. The process parameters for oscillating laser welding have a direct impact on welding quality and carbon emissions. This paper quantifies the carbon emission of lap oscillating laser welding of aluminum alloy sheets to achieve low carbonization of aluminum alloy sheet lap welding. To characterize the welding quality and carbon emission according to the process parameters, it constructs a surrogate model based on a multi-output Gaussian process. The optimal welding objectives are found using the non-dominated sorting genetic algorithm (NSGA-Ⅱ), and the corresponding optimal process parameters. The process test results show that the weld forming quality corresponding to the best process parameters is effectively improved, and the welding defects such as porosity, molten pool collapse, and concave are restrained. The carbon emission in the welding process is effectively reduced by 12.99%, while the maximum bearing capacity of the joint is only reduced by 2.47%, which can significantly reduce carbon emissions in the welding process while maintaining welding quality.