Abstract: This paper deals with the short circuiting time distribution of the droplets of low hydrogen electrodes during manual arc welding.A Type MC-80A dynamic analyzerh as been used with various types of rectifiers as the welding power supply.The observed short-circuit probable distribution belongs to the separated probable model.Let the time corresponding to the maximum short-circuit probable value be t₀,then over 60% of the short-cicuit transition will fall within the range of (t₀±3) ms.The variation range of t₀ for various electrode diameters has been determined after studying the effect of electrode diameter,welding condition and power supply characteristics on t₀.This investigation will help reveal the relation-ship between the spattering of low hydrogen electrodes and the characteristics of power supply and find a more rational method for evaluating the dynamic characteristics of the arc welding power source.