Abstract: Weld appearance and stability of pulsed MIG welding process of aluminum alloy mainly depend on the stability of arc length.In order to obtain the stable welding process and high quality weld bead,the influence of pulsed current parameters on the stability of arc length was studied by welding experiments.The dynamical mathematical model between pulsed current parameters and arc length was established.Meanwhile,the dynamical response of arc length was simulated by varying dutyratio and frequency of pulsed current based on Matlab/Simulink software.At last,the welding experiments were carried out when the duty-ratio and frequency of pulsed current were changed,respectively.The result shows that the established model can reflect the variation of pulsed MIG welding process very well,and the stable welding process can be obtained through changing duty- ratio and frequency of pulsed current,and the sound weld shape was obtained.