Abstract: This paper dcscribes an expert system for aluminum-alloy welding procedure specification.The system selects appropriate welding process,materials and sequence,designs the joint and supplies main process parameters based on the product structure,base metal,workpiece size and requirements of joint property.It is written in Turbo-Prolog and is developed for running on an IBM-PC or compatible computers.The CRT display,excellent in both figures and characters,is in Chinese.The interface between users and the system is friendly.