Abstract: SUS444 ferritic stainless steel was welded by SMAW and MIG welding respecitively. The microstructure and impact toughness of the welded HAZ were compared, and the SEM morphology and energy spectrum analysis of the fracture was carried out.The results show that although small diameter electrode and small welding parameters are used, the grain size of SMAW welding HAZ grows obviously, the room temperature impact energy of 5 mm thick impact samples is lower than 10 J. MIG welding adopts high speed automatic welding, and the heat input is smaller, the grain of welding HAZ doesn't grow significantly, the impact energy of 5 mm thick impact samples reaches more than 40 J at room temperature and more than 10 J at 0℃.