A　novel　welding　process　named　Twin-body　Plasma　Arc　Welding　(TPAW)　is　proposed　in　this　paper.　The　main　arc　in　TPAW　is　established　between　tungsten　electrode　and　guide　electrode.　In　comparison　with　Non-transferred　Plasma　Arc　Welding　(NPAW)　where　one　of　the　arc　terminal　is　the　nozzle,　the　workpieces　are　both　not　connected　into　the　circuit　loop,　and　the　energy　loss　is　less　than　that　of　NPAW.　In　comparison　with　Plasma　Arc　Welding　(PAW)　where　one　of　the　arc　terminal　is　the　workpiece,　the　nozzles　are　both　not　connected　into　the　main　arc　circuits,　and　the　anode　effects　are　not　worked　on　the　workpieces.　To　examine　the　energy　of　these　arcs　by　an　intuitive　way,　a　series　of　experimental　system　were　designed　and　stagnation　ablation　experiments　were　conducted　on　Gr.　D　steel　workpieces.　The　ablation　regions　which　characterize　the　energy　received　by　the　workpiece　are　observed,　measured　and　analyzed.　It　is　found　that　the　diameter　of　ablation　region　(i.e.,　the　energy　received　by　the　workpieces)　from　TPAW　is　smaller　than　that　of　PAW,　but　is　much　larger　than　that　of　NPAW,　as　increasing　the　welding　current　and　plasma　gas　flow　rate.　The　welds　by　TPAW　have　smaller　MZ　area　and　smaller　HAZ　area　but　similar　penetration　in　comparison　with　those　by　PAW,　the　ones　by　NPAW　could　not　observe　MZ　or　HAZ　under　the　same　parameters,　indicating　that　the　total　heat　input　distribution　of　TPAW　is　smaller　than　that　of　PAW　and　much　larger　than　that　of　NPAW.　This　tendency　provides　a　possible　method　to　better　control　the　energy　of　plasma　arc　and　expand　the　application　of　plasma　arc.　(C)　2016　The　Society　of　Manufacturing　Engineers.　Published　by　Elsevier　Ltd.　All　rights　reserved.