Simulation was carried out on the aerodynamic characteristics of train consisting of 3~8 cars running at the speed of 350 km?¤h-1 in crosswind with different velocity. Dimensionless relationship was established between the drag coefficient of train and the number of train formation. Results show that the analysis on the aerodynamic characteristics of train that consists of 3 cars can't replace that of train consisting of other number of cars. The drag coefficient of different train formation increases with the increase of crosswind velocity, and the drag coefficient of train that consists of 3 cars is lower than half of that of 8 cars. The lateral force coefficient and overturning moment coefficient of train decrease with the increasing number of cars that compose a train. The number of cars has less influence on the drag coefficient, lift coefficient, lateral force coefficient and overturning moment coefficient of head car, but it has greater influence on those of tail car. The lateral force coefficient and overturning moment coefficient of head car are obviously higher than those of intermediate car and tail car. The maximum overturning moment coefficient of tail car is less than 0.4, while that of head car reaches 0.7. As the aerodynamic safety of head car is lower than that of other cars, estimating the aerodynamic safety of the whole train based on the aerodynamic safety of head car tends to be conservative, but it's reasonable and feasible.