Additive　manufacturing　(AM)　technology　has　drawn　tremendous　attention　in　producing　lightweight　and　complex　metallic　components.　In　this　work,　a　thin　wall　of　AZ31　Mg　alloy　with　fine　equiaxed　grains　was　fabricated　via　gas　tungsten　arc-based　wire　arc　additive　manufacturing　(WAAM-GTA)　technology.　The　grain　structure,　dislocation,　and　texture　of　the　hot-rolled　and　WAAM-GTA　AZ31　samples　were　analyzed　by　EBSD,　while　the　matrix　and　dispersed　phases　were　characterized　by　EDS　and　X-ray　diffraction.　The　3D　porosity　of　samples　was　examined　quantitatively　by　an　X-ray　computed　tomography　(XCT).　The　results　show　that　dominated　equiaxed　α-Mg　grain　structure　was　obtained　together　with　negligible　precipitated　phase.　The　mechanical　properties　of　WAAM-GTA　AZ31　were　superior　to　their　cast　counterparts　and　close　to　those　of　wrought　AZ31,　and　their　correlation　to　microstructure　and　defects　were　explored.　Moreover,　the　WAAM-GTA　AZ31　showed　excellent　electromechanical　corrosion　performance　in　3.5　%　NaCl　solution　as　compared　to　the　hot-rolled　AZ31　plate.　The　WAAM-GTA　technology　therefore　offers　new　routes　to　fabricate　AZ31　Mg　components　with　equiaxed　grain　structure,　as　well　as　favorable　mechanical　properties　and　electromechanical　corrosion　performance.　©　2021　Elsevier　B.V.