Here,we　compare　the　porosity,microstructure　and　mechanical　property　of　4047　Al-Si　alloys　prepared　by　wire-arc　additive　manufacturing(WAAM)and　conventional　casting.X-ray　microscopy　reveals　that　WAAM　causes　a　higher　volume　fraction　of　gas　pores　in　comparison　with　conventional　casting.Effective　refinements　of　α-Al　dendrites,eutectic　Si　particles　and　Fe-rich　intermetallic　compounds　are　achieved　by　WAAM,resulting　from　its　rapid　solidification　process.Both　ultimate　tensile　strength(UTS,up　to　205.6　MPa)and　yield　stress(YS,up　to　98.0　MPa)are　improved　by　WAAM　at　the　expense　of　elonga-tion　after　fracture.The　mechanical　property　anisotropy　between　scanning　direction　and　build　direction　is　minimal　for　alloys　via　WAAM.Additional　microstructure　refinement　and　strength　enhancement　are　enabled　by　increasing　the　travel　speed　of　welding　torch　from　300　to　420　mm/min.