Based on carbon steel car body,the key structure of rail transit demand for laser wire filling welding technology,according to the different thickness plates butt joints of carbon steel for car body with the thickness of 2.5 mm and 4 mm,systematically research on laser wire filling welding process and welding procedure qualification,provide reliable technical guarantee for subsequent carbon steel car body structure of laser wire filling welding process production application.The results show that,the welding joint and bending specimens with no defects such as porosity crack,which shows that laser filling welding joint has excellent welding quality.The joint tensile strength at around 480 MPa and it meets the requirements of the base metal.From the point of fracture of the tensile samples,they are all broken in the base metal,indicating that the tensile test reflects the strength test results of the base metal,and that welding joint can meet the design requirements of the structure for strength.