Abstract: The fuel economy and stability of vehicle in high-speed driving is directly related to the aerodynamic drag and lift of the vehicle. Compared with traditional fuel vehicles, reducing aerodynamic drag is much more important for electric vehicle in increasing driving mileage and lowering energy consumption. In this paper, Reynolds time-average scheme is adopted to conduct a vehicle external flow field simulation on a battery electric SUV at a speed of 120 km/h, with the results of drag and lift coefficients compared with that of the wind-tunnel test of clay model of the same scale. The common Realizable k-ε turbulent model is used to perform a simulation optimization on the rear spoiler of that SUV to study the effects of the different declined angles of the upper surface of spoiler on the drag and lift coefficients of vehicle. Furthermore, on the basis of best angle obtained, the optimal state of rear spoiler is determined by the comparatively analysis on five different types of through holes on spoiler. The results of final validation test show that the aerodynamic drag coefficient reduces by 3.9%, while aerodynamic lift coefficient increases, but in acceptable range

Key words: electric SUV, rear spoiler, aerodynamic drag, aerodynamic lift, simulation analysis