In this paper it is proved that the calculation pre-cision of the outside flow field of the van-body truck using RNG k-εturbulence model is higher than that using standard k-εturbu-lence model by means of experiments. The calculation results of the outside flow field of a certain domestic van-body truck are given. And by analyzing and comparing the different tail flow plots, the tail flow structural characteristics and the relationship between the position and the intensity of the tail vortex and the aerodynamic drag is obtained, which can direct the design of the outside aerodynamic shape of the van2body truck.