The　twin-body　plasma　arc　has　the　decoupling　control　ability　of　heat　transfer　and　mass　transfer,　which　is　beneficial　to　shape　and　property　control　in　wire　arc　additive　manufacturing.　In　this　paper,　with　the　wire　feeding　speed　as　a　characteristic　quantity,　the　wire　melting　control　ability　of　twin-body　plasma　arc　was　studied　by　adjusting　the　current　separation　ratio　(under　the　condition　of　a　constant　total　current),　the　wire　current/main　current　and　the　position　of　the　wire　in　the　arc　axial　direction.　The　results　showed　that　under　the　premise　that　the　total　current　remains　unchanged　(100　A),　as　the　current　separation　ratio　increased,　the　middle　and　minimum　melting　amounts　increased　approximately　synchronously　under　the　effect　of　anode　effect　power,　the　first　melting　mass　range　remained　constant;　the　maximum　melting　amount　increased　twice　as　fast　as　the　middle　melting　amount　under　the　effect　of　the　wire　feeding　speed,　and　the　second　melting　mass　range　was　expanded.　When　the　wire　current　increased,　the　anode　effect　power　and　the　plasma　arc　power　were　both　factors　causing　the　increase　in　the　wire　melting　amount;　however,　when　the　main　current　increased,　the　plasma　arc　power　was　the　only　factor　causing　the　increase　in　the　wire　melting　amount.　The　average　wire　melting　increment　caused　by　the　anode　effect　power　was　approximately　2.7　times　that　caused　by　the　plasma　arc　power.　The　minimum　melting　amount　was　not　affected　by　the　wire-torch　distance　under　any　current　separation　ratio　tested.　When　the　current　separation　ratio　increased　and　reached　a　threshold,　the　middle　melting　amount　remained　constant　with　increasing　wire-torch　distance.　When　the　current　separation　ratio　continued　to　increase　and　reached　the　next　threshold,　the　maximum　melting　amount　remained　constant　with　the　increasing　wire-torch　distance.　The　effect　of　the　wire-torch　distance　on　the　wire　melting　amount　reduced　with　the　increase　in　the　current　separation　ratio.　Through　this　study,　the　decoupling　mechanism　and　ability　of　this　innovative　arc　heat　source　is　more　clearly.