The　process　window　for　conventional　friction　stir　welding　(FSW)　of　Al　and　Mg　alloys　is　narrow　and　the　maximum　tensile　strength　and　elongation　are　162.2　MPa　and　5.5%,　respectively.　The　dissimilar　Al　and　Mg　alloys　fabricated　by　pulse　current　assisted　FSW　was　studied　through　a　combination　of　microstructure　analyses　and　mechanical　properties　to　achieve　the　best　performance.　With　increasing　pulse　current,　the　tensile　strength　and　elongation　increased　to　215.7　MPa　and　5.24%,　respectively,　and　the　fracture　type　has　changed　from　brittle　fracture　to　compound　fracture.　The　process　window　was　expanded　via　electrically　assisted　effect.　And　cracks,　tunnels　and　other　defects　occurring　in　conventional　FSW　of　Al　and　Mg　were　eliminated　by　pulse　current,　effectively　inhibiting　the　thickness　and　quantity　of　the　intermetallic　compounds　in　the　band　structure　zone　and　the　Al-Mg　interface　and　improving　the　joint　efficiency.