This study investigates the laser-MIG hybrid welding of 20 mm thick 6005A-T6 aluminum alloy components for railway vehicles, aiming to optimize welding parameters and achieve high-quality joints. Through optimization of groove dimensions, the use of a U-shaped groove with a root face height of 8 mm and an assembling clearance of 2 mm, coupled with a three-layer and three-pass welding method, yielded optimal results. The microstructures in the weld center and near the fusion line were equiaxed crystal and columnar crystal respectively. Compared with the filling and covering weld zone, the equiaxed crystal size was coarsest and the columnar crystal zone was widest in the backing weld zone. The microhardness of the weld zone and heat affected zone was lower than that of the base metal, and the lowest microhardness was found near the fusion line. Despite this, the average tensile strength of the joints reached 191 MPa, representing 76% of the base metal strength. The samples fractured near the fusion line, and the fracture morphologies generally showed the ductile-brittle mixed fracture features.