For adjacent tunnels，the pollution air at upstream of tunnel will affect the downstream tunnel and deteriorate its operation environment.Taking realizable k-ε 3D turbulent model and multicomponent diffusion transfer as physical calculation model, the article used FLUENT calculation software to simulate the concentration distribution of different pollutants between the upstream and downstream of tunnel，and the impact of pollution air from upstream export on the downstream of tunnel in different distances and different air velocities. Meantime, it used theory of wall-attached jet to carry out theoretical analysis. The results showed that the rate of secondary pollution for adjacent tunnel is less than 5% when the distance between tunnels is longer than 400 m and wind speed is lower than 2 m/s. When the wind velocity of upstream tunnel is 2.5 m/s, the theoretical value by calculation is basically in agreement with simulation result.