Abstract: High spatter is the main problem of the short circuiting transfer welding for long time.Constraining transient state short current is an effective method of reducing the spatter.This paper first states the basic principle of constraining transient state short current.Base on the constraining waveform's characteristic,three main constraining parameters(the constraining time,the width of constraining pulse width modulation pulse and the current after constraining) are put forth.From the aspect of electromagnetic force in the short-circuit process,the relationship of these parameters and the effect on constraining transient state short current are analysis.Finally,the correctness of the above analysis is verified by experiments.