For the commercial vehicle headlamp jitter problem when idling, the mechanism to generate idle jitter was studied, and the vibration source and transmission path were tested and analyzed. The natural frequency and vibration types of the headlamp assembly were analyzed using CAE simulation technology. The simulation results showed that the frequency of the headlamp assembly and the vibration source overlap resulting in resonance. After CAE analysis, an optimization scheme about adding a support between the headlamp and the lower protection was proposed. The simulation results showed that the headlamp’s natural frequency was far from the vibration source frequency, it was 6Hz between them. So it solved the headlamp idling jitter problem effectively. The substantial vehicle tests verified the effectiveness of the optimization scheme.