Abstract: In order to optimize the CMT welding process of inlet parts of aerospace products, the butt welding of 3 mm thick 5083 aluminum alloy plate was carried out by using optimized parameters. The size, microstructure and mechanical properties of the weld seam without groove and with groove were compared.It is found that the groove structure can make the weld seam more flat and reduce the front reinforcement. For the case without groove, the weld seam structure is equiaxed crystal, and the local structure has a tendency of columnar crystal from bottom to up. For the case with groove, the weld structure presents columnar crystal obviously growing to the center. The coarse grains of the heat affected zone of the weld seam without groove lead to the reduction of mechanical properties of the weld seam, and it fractures in this position during the tensile test.The heat affected zone of the weld with groove is small, which hardly affects the mechanical properties of the weld, it fractures in the substrate.Consequently, the weld with groove are more conducive to the subsequent forming process of inlet products.