Abstract: The first intelligentialized welding CAPP system was developed by combining expert system based on the current research situation of welding CAPP at home and abroad. This system can complete welding document preparation with its welding process design module, process cards compile module and material cost quota calculation module. Welding process design module can deduce welding process parameters based on welding knowledge base, welding inference engine and welding explanation facility. There are three ways to compile process cards: the typical procedure method, the similar procedure method and the menu method. Thus the user can complete the work easily and fast. By parametric groove and iteration method, the total and every layer consumption of multi-pass welding can be calculated.