Due to increasing energy costs, related environmental impacts, and carbon emissions, sustainable development has become an important task for industry. As one of the important links in mechanical transmission, the shape of a gear transmission occupies a large part of the energy consumption. Moreover, the noise and vibration of a gear drive have great potential to damage operators and mechanical equipment. From the perspective of passive vibration reduction technology, an effective method to reduce vibration and energy consumption is parameter optimization of a weight-reduction hole located in a gear blank. For this reason, a finite element model of a lightened gear was established, and modal harmonic response analysis was carried out. Then, we conducted an excitation experiment on a gear to verify the accuracy of the finite element model and find the damping. Finally, considering the size constraints, the maximum structural damping was taken as a goal for parameter optimization. The results show that the damping characteristics of the lightened gear can be improved through the joint efforts of modeling, analysis, and parameter optimization.