Studies　on　modeling　and　simulation　of　arc　help　to　choose　arc-extinction　methods　and　line-selection　methods　in　distribution　network.　Four　kinds　of　arc　mathematical　equations　are　given　such　as　Cassie,　Mayr,　Schwarz　and　the　cybernetic　model.　Mayr,　Schwarz　and　the　cybernetic　model　are　suitable　for　describing　the　arc　characteristics　when　the　grounding　current　is　small.　The　arc　model　of　Schwarz　and　the　cybernetics　is　established,　and　these　two　models　are　compared　using　a　test　circuit　of　arc　characteristics.　The　cybernetic　model　can　set　arc　length,　reflect　the　arc　fault　conditions　and　apply　to　simulation　of　single-phase　arc　grounding　fault　in　resonant　earthed　system.　The　resonance　earthed　system　model　and　the　cybernetic　model　are　established　by　ATP-EMTP,　and　the　effect　of　arc　length　on　arc　impedance,　steady　and　transient　arc　characteristics　is　analyzed.　The　results　show　that　the　cybernetic　model　is　more　intuitive　and　accurate　to　simulate　arc　grounding　fault　in　resonant　earthed　system.　©,　2015,　Power　System　Protection　and　Control　Press.　All　right　reserved.