With　excellent　beam　quality,　high　wall-plug　efficiency,　low　maintenance　costs,　long　lifetime　of　pump　diodes,　flexible　beam　delivery　and　compact　size,　the　new　fiber　lasers　are　very　attractive　for　welding　and　cutting　various　kinds　of　materials　in　industrial　applications　since　the　short　wavelength　laser　beams　can　be　absorbed　by　almost　all　metals　and　alloys.　Fiber　laser-　metal　inert　gas　(MIG)　hybrid　welding　is　carried　out　onto　TC4　alloy.　The　effects　of　laser-leading　(LL)　and　arc-leading　(AL)　welding　direction　on　top　bead　appearance,　cross　section,　penetration　depth,　width　and　reinforcement　of　welds　are　investigated.　The　results　show　that　the　fiber　laser-MIG　hybrid　welding　in　LL　welding　direction　leads　to　better　top　bead　appearance,　wider　weld　width　and　shallower　penetration　depth,　than　those　in　AL　welding　direction.　The　weld　direction　has　little　influence　on　the　reinforcement　of　the　welds.