The invention discloses a robot automatic welding line for a self-propelled maize harvesting machine chassis. The robot automatic welding line comprises three welding stations being the manual assembling welding station, the robot automatic welding station and the manual repair welding station. The manual assembling welding station comprises a flexible assembling clamp, an automatic conveyor and a buffer tool. The robot automatic welding station comprises a welding robot, a two-shaft gantry sliding table and a rotary positioner. The welding robot is installed on the two-shaft gantry sliding table, and the manual repair welding station comprises a repair welding clamp and a lifting positioner. According to the welding line, workpieces are conveyed among the different welding stations along a conveying channel through an AGV logistics vehicle. The welding line is in a symmetrical robot welding mode, has the outstanding advantage that linear deformation and twist deformation are avoided or reduced after welding, the requirements for the straightness (curvature) specified in national standards can be met after welding, and the welding quality of the maize harvesting machine chassis is ensured.