Abstract: A microcomputer intelligent control system has been developed for self-optimizing of the arc voltage in CO₂ welding process.The system can automatically adjust the arc voltage in accordance with the set welding current value.The major models in the system are the arc voltage fuzzy control model,the welding current control model and the one knob recommending table.The arc voltage fuzzy control model takes the synthetic evaluation value of characteristic parameters in the welding process (the short circuiting transfer frequency f_d,the ratio of arc duration to short-circuiting duration t_as,and the short-circuiting period standard deviationσ) as a basis to optimize the arc voltage value.The testing results show that the developed self-optimizing control system obviously improve the performance of CO₂ welding machine and reduce welding spatter.