The　critical　velocity　of　subway　tunnel　cross-passage　was　investigated　since　the　smoke　control　mode　is　different　from　that　of　road　tunnel　and　larger　blockage　effect　of　train　need　to　be　given　priority.　In　order　to　ensure　an　effective　smoke　control　and　safe　evacuation,　numerical　simulation　and　experimental　study　were　conducted　to　investigate　the　critical　velocity　of　subway　cross-passage.　On　the　basis　of　exiting　critical　Froude　model,　the　influence　of　tunnel　shape,　fire　location　and　train　blocking　on　critical　condition　were　analyzed.　The　results　indicate　that　the　blockage　of　train　has　a　great　influence　on　the　critical　velocity.　With　the　shorter　distance　between　train　and　cross-passage,　the　ventilation　velocity　through　cross-passage　dramatically　increases.　In　addition,　critical　velocity　with　rectangular　tunnel　is　obvious　larger　than　that　with　shield　tunnel.　As　the　fire　source　location　is　closer　to　the　cross-passage,　the　critical　velocity　would　be　greater　and　the　corresponding　Froude　number　would　become　smaller.