More　and　more　urban　traffic　tunnels　are　built　due　to　the　heavy　traffic　in　dense　urban　areas.　Fire　safety　in　tunnels　is　a　concern　due　to　the　large　traffic　flow.　Most　of　the　urban　tunnels　have　slope.　Knowledge　on　smoke　spread　in　titled　tunnel　is　still　limited.　Experimental　studies　on　the　smoke　spread　in　a　titled　tunnel　are　carried　out　by　the　reduced-scale　tunnel　model　tests　and　will　be　discussed　in　this　paper.　Effects　of　the　titled　gradients　and　longitudinal　ventilation　speed　on　the　temperature　distribution　and　smoke　stratification　downstream　from　the　fire　along　the　tunnel　will　be　studied　The　results　show　that　the　smoke　spread　upwards　much　faster　with　the　slop　gradient　increasing,　and　a　thick　smoke　layer　was　formed　when　smoke　moved　to　the　upward　part　of　the　tunnel　and　filled　it　up.　The　ventilation　speed　had　a　great　influence　on　temperature　distribution　along　the　tunnel,　and　the　smoke　stratification　will　be　distributed　when　the　longitudinal　ventilation　speed　becomes　large.　Lower　ventilation　speed　should　be　adopted　at　the　beginning　to　ensure　the　smoke　downstream　of　the　fire　keep　stratified　to　give　the　tunnel　users　more　time　to　escape.　(C)　2012　The　Authors.　Published　by　Elsevier　Ltd.