Aimed　to　provide　a　more　close-to-reality　and　rapid　calculation　method　for　optimization　design　of　low　voltage　circuit　breaker　with　complex　mechanism,　an　interruption　model　is　constructed,　which　can　describe　the　coupling　of　air　blast　process　with　arc　model,　complex　mechanical　movement,　magnetic　field,　and　electric　circuit.　The　model　is　based　on　the　non-stationary　gas　conservation　equations,　and　considers　the　influence　of　the　chamber　structure　on　the　gas　dynamics.　To　realize　the　interaction　between　the　arc　movement　and　the　gas　flow　simply,　on　the　one　hand,　the　moving　electric　arc　is　deemed　an　energy　input　source　of　the　chamber　gas.　On　the　other　hand,　the　movement　equation　of　the　arc　considering　action　of　the　gas　flow　is　built.　With　this　model,　the　general　principle　of　the　chamber　gas　flow,　arc　voltage　and　current　during　the　interruption　process　of　an　actual　breaker　are　calculated　and　compared　with　the　experiment　results.　As　an　application,　the　influence　of　the　chamber　vent　size　on　the　arc　movement　is　studied　with　the　model　as　well.