Abstract: A microcomputer controled SCR welding rectifier experimental system designed and made by authors has been applied for a serial welding test.By means of changing the preset value of programming parameters,the dynamic behavior parameter Ihd, which is the output current overshoot of the rectifier on the load-short circuit transition,has been adjusted systematically so as to investigate the effect of the dynamic characteristics of the SCR welding rectifier on the welding spatter quantiatively. The experimental results show that the dynamic criterion (Ihd/Ih),i.e.the ratio of current overshoot Ihd to output loading current of the rectifier,has a great effect on the relative ratio of welding spatter △M.Under the testing condition of this paper, the effect of (Ihd/Ih) on the △M can be conclued as follows:there is a minimum value of △M corresponding to the value 1.6—2.0 of (Ihd/Ih);there is an obviously increasing of △M while the value of (Ihd/Ih) is over 2.0 or below 1.6.