Electrical　property　is　a　key　factor　to　determine　performance　and　characteristic　of　welding　arc.　In　this　study,　the　electrical　property　distribution　of　welding　plasma　arc　was　investigated　by　means　of　a　novel　dual　active　probes　method.　Experiments　were　conducted　with　different　positions　and　polarities　of　two　active　probes　in　plasma　arc　column,　to　address　the　distribution　of　electrical　conductivity　in　arc　column　and　the　effect　of　detection　current　direction　in　both　radius　and　axis.　The　trend　of　radial　electrical　conductivity　in　different　cross　section　of　arc　column　could　be　got　via　calculating　the　V-I　ratio.　When　the　probe　tips　are　symmetric　about　the　center　of　the　arc　column,　the　gradient　of　the　arc　electrical　conductivity　in　radial　is　greater　than　that　in　axial.　When　the　probe　tips　are　asymmetric　about　the　center　of　the　arc　column　in　the　same　arc　cross　section,　the　V-I　ratio　get　from　the　situation　that　the　negative　probe　far　from　arc　center　is　larger　than　that　as　negative　probe　closer　to　arc　center.　When　the　different　polarity　probes　moved　in　axis　direction,　the　negative　pole　effect　and　the　arc　voltage　fall　both　act　on　the　V-I　ratio　of　axis　direction,　to　make　it　appear　contradictory　trends.　Such　a　study　is　significant　in　helping　to　develop　and　optimize　novel　plasma　arc　heat　source　such　as　cross　arc　and　coupling　arc.　(C)　2018　The　Society　of　Manufacturing　Engineers.　Published　by　Elsevier　Ltd.　All　rights　reserved.