Abstract: Regarding the disaster prevention and rescue problems of high-speed railway tunnels in dangerous moun? tainous areas, a new type of emergency rescue station structure suitable for such tunnels is put forward based on actual conditions of Mabaishan Tunnel in Qinling Mountains. Using FDS software it simulates the smoke diffusion under longitudinal ventilation in a scenario of train fire in the tunnel, and determines the length parameter of the isolation area for emergency rescue station, which is not given in specifications. The results show that: (1) the new structural type of the emergency rescue station of Mabaishan Tunnel in Qinling Mountains should include evacuation area, isolation area and refuge area for rescue. (2) By FDS numerical simulation, the diffusion length of smoke along the downhill direction is 295 m without considering longitudinal ventilation, and the longest diffusion length of smoke along the downhill direction is 980 m with considering longitudinal ventilation. It is recommended to set the length of isolation area as 1 000 m.