The optimization of aerodynamic shape of headlamp is helpful to enhance automotive aerodynamics and appearance. As aerodynamic shape parameters of headlamp are complex and their values are ambiguous, the paper optimizes aerodynamic shape parameters of headlamp by use of orthogonal experimental design based on numerical simulation. According to aesthetics and function, the paper divides aerodynamic shape parameters of headlamp into primary and secondary parameters, makes discretization for the parameters, gives out their constraints and value ranges, and obtains simplified optimal modeling for aerodynamic shape of headlamp. On this base optimal combination of aerodynamic shape parameters of headlamp orthogonal table could be gotten by using of orthogonal table, which improves optimal analysis efficiency. And numerical example shows the method is effective.