A composite forming system of adding/reducing materials,which is integrated with arc welding and reducing materials,has been developed. The system is composed of the main control part,the additive part,the reducing part,the changing tool mechanism,the equipment foundation part and the auxiliary mechanism. The motion mechanism and the numerical control system are integrated to perform the movement track of the additive and reducing material processing. The welding torch is set as a tool. The tool changing system can replace either the tool in the tool bank or the welding torch. The power supply equipment with CMT function and the wire feeding mechanism with a variety of wire diameter are selected. The main control system based on industrial control computer is developed. Through the actual sample processing and the scrap part repairing,the developed equipment has the capability of adding/reducing material compound processing,low cost and rapid manufacturing speed,and can meet the demands of various parts.