Robotic welding is usually used in the mass production of standard components,but it is not well applied in the small batch production of non-standard components due to the long teaching time when components change. With the increassing demands of automation in the heavy industry,modular design is conducted for shield structure,which a large non-standard product in shield tunneling machine,by taking advantage of automatic characteristics and flexibility of robotic welding station. Working modular is established according to the structure features and dimensions,which is then optimized to different robotic welding stations,namely tailor blank welding and assembly station for body of shield structure and multiple robotic welding stations for component. In such a way,the production line of shield structure is upgraded to manufacture automatically and in module. The production efficiency and quality are greatly improved. It can provide a paradigm for upgrading the manufacturing of such large non-standard products.