Air　circuit　breaker　(ACB)　is　widely　used　in　power　distribution　system.　The　movable　contact　of　ACB　consists　of　multiple　parallel　contacts　and　the　arc　will　be　ignited　between　arcing　contact　and　static　contact　when　the　short-circuit　current　appears.　This　paper　focuses　on　the　arc　evolution　process　at　various　currents　in　multiple　parallel　contact　systems.　A　3-D　magnetohydrodynamic　model　of　a　multiple　parallel　contact　structures　is　developed.　In　this　model,　the　anode　consists　to　five　parallel　contacts,　and　they　are　separated　by　insulation　material.　The　near-electrode　layer　with　a　nonlinear　voltage-current　density　characteristic　is　modeled　to　describe　the　near-electrode　voltage　drop,　and　the　difference　between　near-anode　and　near-cathode　layers　is　considered.　The　magnetic　vector　potential　approach　is　adopted　to　calculate　the　time-varying　electromagnetic　field　produced　by　the　current　loop.　The　arc　evolution　processes　at　various　currents　are　analyzed　by　current　density　and　arc　voltage.　It　is　noted　that　the　anode　arc　root　appears　on　multiple　contacts　with　the　increase　of　current.　The　arc　evolution　process　mainly　depends　on　the　arc　resistance　characteristic.