Laser-arc　hybrid　welding　is　considered　one　of　the　most　promising　joining　technologies　and　has　worldwide　been　elaborated　for　various　applications　in　automobile,　shipbuilding,　and　rail　vehicle　industries　since　1980s.　Compared　to　laser-MIG　hybrid　welding,　laser-TIG　hybrid　welding　with　filler　wire　possesses　the　advantages　of　more　stable　process　and　higher　weld　quality.　The　basic　objectives　of　this　study　are　to　optimize　the　experimental　setup　and　understand　the　fundamental　phenomena　in　laser-TIG　hybrid　welding　with　filler　wire.　For　this　purpose,　a　Nd:YAG　laser　with　an　output　power　of　2.5kW　and　a　DC　TIG　welder　were　used　in　this　experiment.　Bead-on-plate　welding　was　performed　on　low　carbon　steel.　The　influences　of　welding　parameters　on　the　weld　depth,　weld　width　and　the　process　stability　were　analyzed.　The　results　demonstrate　that　the　introduction　of　a　TIG　arc　to　the　laser　welding　process　with　filler　wire　can　increase　the　welding　efficiency　and　improve　the　weld　formation.　Among　various　parameters,　the　distance　between　the　two　heat　sources　has　important　influence　on　the　weld　profiles　and　welding　with　a　helium　arc　can　obtain　a　weld　with　deeper　penetration　and　greater　width　than　with　an　argon　arc.