Abstract: In actual tunnel fire, the fire source location is often not fixed. For a certain gradient tunnel, due to its special structure, in the event of a fire, the damage caused is much larger than other types of fire.Based on FDS software, this paper simulates and calculates the tunnel with a gentle slope tunnel.We investigated the effect of transverse position of fire source on the distribution of tunnel ceiling smoke, the vector distribution of flue smoke flow velocity at the height of 1.6 m and the distribution of temperature drop along roof flue smoke, and compared with the numerical simulation results of horizontal tunnel withhorizontal tunnel.The research results show thattunnel ceiling smoke with the tunnel wall and the distance decreases.From the symmetrical V-type movement to asymmetric S-type movement, gentle slope tunnel are noticeable, and ceiling flue gas temperature along the outlet are exponentially reduced, and the temperature coefficient increases with the decrease of the distance between the source of fire and the tunnel wall, and roof low temperature gradually approaches the tunnel wall and the range gradually increases, and horizontal tunnels have a lower temperature range than gentle slope tunnels.