Abstract: A new welding method-activating flux MIG(AMIG) welding was proposed in this paper, which can obtain welded joint with high quality and reduce lack of fusion. The arc morphology during this welding method were collected and analyzed. The results show that the current density in A-MIG welding was higher than that in conventional MIG welding. Based on the analysis with scanning electron microscope and transmission electron microscope, the inspection results by comparing A-MIG welding and conventional MIG welding show that the addition of activating flux did not affect precipitated phases and distribution of Mn, Cr and Ti alloying elements.