With　the　rapid　development　of　construction　and　management　of　subway　in　China,　fire　safety　has　drawn　more　attention　in　subway　tunnel.　It　is　necessary　to　study　and　simulate　the　situations　like　the　power　and　position　of　fire,　smoke　diffusion,　temperature　distributing　and　fan　operation,　and　the　result　can　help　analyzing　fire　state　at　the　pot,　controlling　the　fire　and　evacuating　people.　A　three-dimensional　mathematical　model　of　the　smoke　movement　in　tunnel　fires　was　established.　Finite　volume　method　was　used　to　discretize　the　governing　equations　and　the　SIMPLE　algorithm　was　employed　to　solve　the　governing　equations.　A　scaling　model　(1:8)　of　the　subway　tunnel　was　built　up　based　on　similarity　theory.　The　steady　and　unsteady　fire　situations　of　experiment　have　been　done　on　the　scaling　benchmark　model.　Further　computer　simulation　will　also　be　applied　on　it　and　compared　with　the　result　in　experiment　to　validate　the　usefulness　of　simulation.　In　experiment　we　considered　both　different　positions　of　fire　on　the　train　and　different　starting　times　of　exhaust　fan　in　the　tunnel.　The　disciplines　of　smoke　temperature,　smoke　diffusion　and　wind　velocity　have　then　been　compared　with　the　situation　changes.　The　study　brings　forward　a　conclusion　which　is　useful　to　analyze　people　evacuating　and　fire　controlling　in　emergent　of　tunnel　fire　in　Beijing　subway　system.