Abstract: Welding and its assemblies are the key links and necessary technological means of rail transit equipment manufacturing. Ensure the standardization and relevance of the process information of each process, as well as the intuitive and effective production guidance, which is conducive to improving product quality and production efficiency. A welding process development model based on a 3D design model is designed to meet the transformation and upgrading demands of the digital manufacturing of rail transportation equipment. With the data construction method of abstract structure to instantiation mapping, a 3D welding process system is developed based on the C# language. Based on establishing a clear field system, information fusion and visual operation guidance across production stages are achieved via building template processes, instantiating process fields, and associating 3D models and workstations. The system's effectiveness was validated by designing and applying a 3D welding process for a locomotive bogie frame. The results indicate that the system is flexible, efficient, highly visualized, and easily traceable. It effectively improves the production mode of operation and has a certain application value.