Abstract: In this paper,quantitative analyses about the effect of dynamic characteristics of SCR arc welding rectifier on spatter have been made by using microcomputer experimental and data analyzing system.The statistical data derived from welding tests showed that there is a certain qualitative relationship between the arc welding spatter and the dynamic criterion I_hd/I_h,i.e.,the ratio of overshoot current to load current on the load-short circuit transition of welder.Further studies with high speed photography and synchronous measurement of welding current revealed that the said relationship is in fact mainly the influence of the dynamic behavior of the rectifier on the transient current value at the moment when the short circuiting transfer is over.In the case of the value of I_hd/I_h being over 2.0,the current output from the rectifier to restrike arc at that moment will be so large that the welding pool is strongly impacted to cause spatter.