The effect of headlamp modeling on automotive aerodynamics was studied by wind tunnel tests. Firstly, the effect of Reynolds number on drag coefficient of automotive scaled down models was studied under different velocity of flow to verify the rationality of selecting scale for scaled down model and setting inlet boundary condition. Secondly, drag coefficient of automotive scaled down models with different headlamp modeling design were measured. Thirdly, the distribution of surface pressure on central symmetry plane and headlamp was measured and analyzed. It also validated the validity of preceding numerical simulation. It is of importance to guide the headlamp modeling design and automotive modeling design.