In order to optimize the aerodynamic drag coefficient of a van type truck, three kinds of pneumatic drag reducing devices such as the bionic drag reduction structure of the front part of the cab, the top and side vortex generators, and the bottom vortex generator are designed. The effects of main parameters of three kinds of single pneumatic drag reducing devices on aerodynamic drag are studied. The drag reduction effect of each pneumatic drag reducing device is analyzed in detail from three aspects:speed trajectory, pressure distribution and turbulent kinetic energy distribution,on the basis of which, the main parameters of the three kinds of pneumatic drag reducing devices are optimized by orthogonal test method, and the truck model with optimal drag reduction is obtained. The research shows that the influence of the length of the front part of the cab on the aerodynamic drag coefficient of the truck is greater than that of the tilt angle. The inclination angle and length of the optimal truck head shape are 135ånd 300 mm, respectively. The aerodynamic drag coefficient of the model is 0.721 4, and the drag reduction rate is 8.93% compared with the original model of the truck. The height and position of the vortex generator have a great influence on the drag reduction effect of the truck. The vortex generator can increase the energy of the flow field in the separation area of the tail of the truck, and reduce the tail vortex area and the pneumatic differential pressure. The order of influence of the three kinds of pneumatic drag reducing devices on the aerodynamic drag coefficient of the truck is as follows:bottom vortex generator, the bionic drag reduction structure of the front part of the cab, and top and side vortex generators. The air drag coefficient of the optimal van type truck model is 0.683 3, and the optimal drag reduction rate of the composite drag reducing device is 13.8%.