Abstract: The pulsed CO₂ welder, which controls its pulse current wave by the constant current control method, is need to solve an important problem of automatical regulating the pulsed CO₂ welding arc voltage, since without the constant arc voltage output curve it will lose the ability of self-adjusting arc length.In this paper, a new method is proposed for self-adaptive control of the pulsed CO₂ welding arc voltage.Its operating principle is through arc voltage feedback control of the peak current time to make the pulsed CO₂ welder yield sloping output characteristics so as to realize the self-adaptive adjusting of its arc voltage.By taking the slope rate as the criterion of its algorithm, this control method can determine the slope rate of welder output curve and adjust the self-adaptive control intensity in quantity.