In this study, based on the SST K-to turbulent model, the IDDES method is used to simulate the unsteady aerodynamic performance of trains with respect to different lengths of the tapered nose of the train (8 m and 12 m). The numerical simulation used in this study is verified through wind tunnel tests. The effects of the length of the tapered nose of the train on the aerodynamic performance, such as the train forces, boundary layer, velocity distribution, pressure distribution, and flow structure around the train, are elucidated via comparing and analyzing the obtained results. The results indicate that the effect of the length of the tapered nose of the train on the drag force of the tail car and lift force of the head car is stronger than the effect on other cars, and the C-d value of the tail car decreases by 30.53% and the C-l value of the head car increases by 87.98%. Increase in the length of the tapered nose of the train decreases the fluctuation of the drag and lift forces of the train, especially the head car. It is also observed that the boundary layer thickness around the train is decreased with the increase in the length of the tapered nose of the train. Moreover, it is observed that vortex drag is the primary factor in the aerodynamic drag of the tail car and that vortex drag primarily depends on the length of the tapered nose of the train. (C) 2018 Elsevier Ltd. All rights reserved.