Abstract: A microcomputer control system for arc selding with IGBT inverter power source was developed in this paper,which is able to meet the requirement of the welding process by adjusting the output characterristic according to arc states.The system reduses instantaneous short circuit possibility and spatter during CO₂ welding process,increases burning arc power and improves bead formation.Experiments have proved that it has strong adaptability to distrurbance of arc length,and is particularly suitable for semi-automatic welding process.