| The bogie areas of a high-speed train are the focus of aerodynamic drag reduction research. A 7-parameters model of high-speed train underbody structure was established by spline curve method. The influence laws between underbody structure parameters of a high-speed train and aerodynamic drag were studied by computational fluid dynamics and Latin hypercube sampling (LHS) experimental method. The results show that 27%, 37%, 39% and 22% aerodynamic drag changed in the three cars model, head, middle and tail car with varying underbody parameters, respectively. The height of side cover, height of cowcatcher, radius of bogie cavity leading edge are most sensitive parameters to drag of three car model. However, the influences between underbody structure parameters and the aerodynamic drag are different for the three cars model and each car model. In order to achieve a better drag reduction, it is necessary to consider the aerodynamic design of underbody structures of the head, middle and tail car, respectively. The underbody structure parameters mainly influence the aerodynamic drag of the underbody structure by affecting the mean velocity beneath the train body, therefore, the aerodynamic drag of a high-speed train is influenced.