To prepare high-quality aluminum alloy thin-walled parts and extend the service life of marine engineering equipments, the effect of laser forging composite arc additive manufacturing technology on the microstructures, porosities, and mechanical properties of thin-walled parts are studied. The results show that laser forging can effectively promote grain refinement, reduce the number and size of pores, and significantly improve the density of deposited layers and overall manufacturing quality. Microhardness and tensile experimental results show that, compared with thin-walled parts without laser forging process, the microhardness of the thin-walled parts with laser forging technology increases by 21.07%; landscape and portrait tensile strengths increase by 4.62% and 13.63%, respectively; and the elongation after breaking is also significantly improved. Therefore, laser forging can significantly improve the microstructures and mechanical properties of 5083 aluminum alloy thin-wall parts, providing an effective technical way for efficient repair and performance optimization of marine engineering equipment.