In　view　of　two　underground　traffic　tunnels　with　longitudinal　ventilation　system　in　Beijing,　methods　of　combined　with　full-scale　tests　and　numerical　simulations　are　used　to　research　the　ventilation　status.　The　ventilation　ability　of　an　axial　fan　and　jet　fans,　and　the　settings　of　boundary　conditions　in　numerical　simulations　are　investigated.　From　test　and　simulation　results,　it　is　found　that　equipping　diversion　shutter　at　the　air　opening　of　axial　fan　can　enhance　its　effect　of　air　supply　to　tunnel　downstream,　and　the　diversion　shutter　can　be　modeled　by　two　vertical　bevel　faces　at　the　edge　of　the　air　opening.　Furthermore,　the　jet　fan　is　suggested　to　be　applied　with　pressure　boundary　condition.