A　hybrid　arc-wire　welding　method　based　on　the　variable　polarity　plasma　arc　(VPPA)　and　variable　polarity　pulse　metal　inert-gas　(VP-PMIG)　was　proposed　for　manufacturing　aluminum　alloys.　This　paper　aims　to　clarify　the　decoupling　control　process　of　heat　and　mass　transfer　in　the　hybrid　welding　process.　To　understand　the　arc　physics　and　analyze　the　mass　transfer　behavior,　the　hybrid　arc　shape　and　droplet　cross-sectional　area　with　different　parameters　were　obtained　by　high　speed　video　photography.　Further,　the　melting　area　of　the　base　metal　was　analyzed　by　macro-metallography　of　the　weld　bead　cross-section　to　study　the　heat　transfer.　It　is　found　that　the　hybrid　arc　shape　changes　with　time.　The　VPPA　main　arc　is　deflected　to　one　side　by　the　VP-PMIG,　making　the　temperature　distribution　asymmetric,　and　during　the　VP-PMIG　pulse　necking　occurs.　The　cross-sectional　area　of　the　droplet　is　more　obviously　affected　by　the　VP-PMIG　current　than　the　VPPA　current.　Meanwhile,　the　VPPA　current　dominates　the　melting　area　of　the　base　metal.　Therefore,　we　conclude　that　heat　transfer　to　the　base　metal　is　from　the　VPPA,　while　droplet　transfer　is　mainly　controlled　by　the　VP-PMIG　arc.　These　conclusions　are　confirmed　by　analyzing　the　decoupling　degree　of　heat　and　mass　transfer　of　the　base　metal　by　the　VPPA　and　VP-PMIG　arc.