An unsteady three-dimensional analysis of the ventilation performance is carried out for different ventilation strategies to find out a ventilation method with a high performance in a subway tunnel.The natural ventilation performance associated with a train-induced air flow in a subway tunnel is examined.The dynamic layering method is used to consider the moving boundary of a train in the current CFD method.The geometries of the modeled tunnel and the subway train are partially based on those of the Seoul subway.The effects of the structure of the ventilation duct and the geometry of the partitions on the ventilation performance are evaluated.The results show that the combined ventilation ducts (to be designed),and the partitioning blocks installed along the middle of tunnel (already in existences) are helpful for air exchange.This study can provide some guidance for the design of ventilation ducts in a subway system.