Abstract: Based on the step response experiment,the welding pool width model of dynamic process in aluminum alloy pulsed metal inert-gas welding was identified by least square method.The input of the model was welding wire speed and base current respectively,and the output was beam width of welding pool.The influence of wire speed and base current on welding pool width was analyzed.It provides the theoretical basis to realize the intelligent control for aluminum alloy pulsed metal inert-gas welding process.