To explore the optimization and design method of non-smooth surface on vehicle body, dimple, convex and groove non-smooth surfaces are respectively arranged at the rear of the MIRA model. CFD and wind tunnel test are adopted to analysis the reduction effects and the drag reduction effects are compared with the original smooth model. The results show that the aerodynamic drag decreases with the decoration of non-smooth surface. In the article, the distance and the height of non-smooth surface are considered as the design variables. Aerodynamic drag is the objective evaluation functions. Sample points are obtained by Latin hypercube sampling method and Kriging approximate model is set up according to sample points and response values. The fitting precision of approximate model is tested. NSGA-II is used in genetic algorithms. Drag reduction effects and mechanism before and after optimization of non-smooth surface model are compared and analyzed. The simulation and test results both show that the aerodynamic drag coefficient are further decreased and the aerodynamic drag reduction rate of dimple, convex and groove non-smooth surface are 6.92%, 4.03%, 4.24%. The optimization method in this article is validity and generality and it provides relative reference for the follow-up research and design of the non-smooth surface characteristic parameters.