As　to　traditional　single　electrode　free　welding　arc,　changes　about　energy　density　of　the　ionizing　region　in　the　center　of　arc　column　is　not　obvious　with　current　increases　due　to　structural　limitations.　In　this　paper,　we　developed　parallel　multi-electrode　arc　discharge　torch　which　is　based　on　the　mechanism　of　self-magnetic　contraction　effect　in　welding　arc,　the　torch　effectively　improve　energy　density　of　ionization　region　in　non-melting　inert　gas　arc,　which　is　proved　by　experiments,　and　we　discussed,　effect　of　the　pulse　input　energy　and　pulse　frequency　to　energy　density　of　the　arc　with　parallel　multi-electrode　torch.　This　study　demonstrated　the　approach　of　improving　the　energy　density　of　arc　ionizing　region　by　self-magnetic　pinch　effect　is　feasible.　©　(2013)　Trans　Tech　Publications,　Switzerland.