In　order　to　improve　the　indoor　air　quality　of　city　transport　system,　the　authors　had　selected　a　public　transport　interchange　station　in　a　comprehensive　transit　hub　as　a　research　object.　Carbon　monoxide　was　selected　as　the　main　pollutant　for　description　of　air　quality.　Ventilation　systems,　bus　traffic　and　passenger　flow,　air　quality　had　been　investigated　by　on-site　survey.　Large　eddy　simulation　technology　had　been　used　to　analyze　indoor　air　quality　of　public　transport　interchange　station.　The　boundary　conditions　were　determined　according　to　the　measured　date.　Indoor　air　quality　results　at　heights　of　0.8　m　and　1.6　m　under　different　time　periods　and　operating　conditions　of　public　transport　interchange　station　were　calculated.　Time　periods　include　the　peak　hour　and　trough　hour.　Results　have　shown　that　carbon　monoxide　concentration　in　peak　hour　is　about　twice　than　that　in　trough　hour　in　most　area　except　the　rear　area　of　the　vehicle.　Air　quality　would　reach　the　harmful　degree　within　5　to　10　minutes　if　the　ventilation　system　is　not　operating.　The　ventilation　system　should　be　operated　during　the　peak　hour　and　intermittent　operation　mode　can　be　adopted　during　trough　hour　in　order　to　meet　the　requirement　of　air　quality　standards.　©,　2015,　Beijing　University　of　Technology.　All　right　reserved.