In this study， a notchback SAE model with a 20° back angle is used as a reference model. The unsteady flow field structure of vortex generators （VGS） and riblets （RTS） on the roof and rear of the inclined plane is studied based on the improved detached eddy simulation （IDDES） turbulence model. The drag reduction mechanism of the two passive control devices is analyzed in detail. In addition， the sound source information of the flow field is extracted， and the noise of the automobile is analyzed by Computational Aeroacoustics （CAA） and Ffowcs Williams-Hawkings （FW-H） equation， and the effect of the two devices on the acoustic characteristics is investigated. The results show that the additional devices can reduce the rear-vortex structure strength， aerodynamic resistance， and pulsating pressure， which not only achieves the effect of drag reduction but also has the effect of noise reduction. The drag reduction rates are 2.41% and 2.76%， respectively， and the maximum reduction values of total sound pressure levels are 9.55 dB and 5.46 dB， respectively.