FDS 6.7.0 was used to simulate the self-extinction of fire in a reduced-scale tunnel under different obstacles locations. The blockage ratio was 65 percent, and the distance between obstacles and fire source was 4m, 6m, 8m, 10m, respectively. Symmetrical blocking method was adopted. A 11.2 kW propane fire was used as the fire source in the simulation. It's found that FDS 6.7.0 could reproduce the self-extinction behavior. The simulated self-extinction time under different obstacles locations shows the same rule as the experimental values but the simulated value of self-extinction time is shorter than the experimental value. The simulation results of smoke and temperature show that the closer the obstacles are to the fire source, the more favorable it is for fire-fighting and evacuation