In order to optimize the bottom flow field of the car while reduce the aerodynamic resistance of the vehicle,the gas flow through the chassis was organized and guided by adding the front and rear wind deflectors to the original model of the vehicle,and the wind tunnel test was conducted to verify the effectiveness and simulation accuracy of the initial optimization scheme.On the basis of the initial optimization scheme,the combination of experimental design,grid adaptive and approximate model was used to make continuously deform and integrated calculation to the wind deflector,and the structure of the wind deflector was further optimized to obtain the final optimization scheme.The results show that the front and rear wind deflectors can be used to smooth the turbulent airflow of the chassis,and the combination of experimental design,mesh adaptive and Kriging approximation model can be used to quickly achieve a greater degree of drag reduction.The final drag coefficient is reduced by 415%.