In order to investigate the effect of environmental wind on a tunnel with one blocked end fire under natural ventilation, a series of numerical simulations were conducted using large eddy simulation method in this study. The tunnel model is established by using the numerical simulation software FDS, and 36 groups of working conditions such as wind speed of 0-5m / s and wind angle of 45-135 are simulated. Combined with the simulation results of smoke spread, temperature and velocity vector, the smoke flow characteristics and temperature distribution characteristics in the tunnel with one blocked are analyzed, and some effects of the changes of ambient wind speed and direction on natural smoke exhaust in a tunnel with one blocked end are obtained.