In　order　to　solve　the　problem　of　ventilation　pressure　loss　in　the　fire　area　under　the　fire　condition,　the　wind　pressure　loss　model　of　the　fire　area　is　established　based　on　the　thermodynamic　equilibrium　relation.　The　semi-empirical　calculation　formula　is　obtained　by　using　the　model　experiment　and　CFD　simulation.　The　validity　of　the　formula　is　verified.　The　results　show　that　the　ventilation　pressure　loss　in　the　fire　zone　is　proportional　to　the　convective　heat　release　rate　at　the　critical　velocity,　which　is　inversely　proportional　to　the　upstream　ventilation　velocity　and　the　tunnel　cross-sectional　area.　The　proposed　formula　is　consistent　with　the　law　of　the　tunnel　fire　test　fitting　formula　that　results　are　close,　in　contrast,　the　advantage　lies　in　a　clear　theoretical　basis　and　ventilation　velocity　values.　The　resistance　of　road　tunnel　ventilation　system　is　calculated　accurately　and　reliably,　and　then　an　effective　emergency　ventilation　operation　program　is　developed.　It　is　necessary　to　consider　the　fire　zone　ventilation　pressure　loss.　The　proposed　ventilation　pressure　loss　formula　can　be　used　for　design　calculation　after　thorough　verification.