The sustainability of today’s industry turned into a critical requirement on account of energy cost increases, environmental pollution, and carbon emissions. As an important segment in mechanical drive, the vibration and noise from gear transmission negatively impact the physical and psychological health of workers and interfere with the machine running. This paper proposes a new temperature-controlled vibration-damping lightening polymer composite gear model with a modified lightweight web structure. The characteristic of polymer (mechanical properties changed by structure temperature) was trying to be used for the gear damping variable control. The spur gear web was replaced with a spoke-like structure connected with a ring structure that adheres to the heating film. That was required to assure torsional rigidity and compliance meanwhile controlling the web structural damping performance. For experimental purposes, the gears were manufactured from three kinds of viscoelastic polymer using additive manufacturing technology. The gear frequency sweeping excitation testbed was built in the experiment. The vibration exciter and gear dynamic responses were measured through the force and torque sensor. In the tests, the modal frequency and damping of gears were measured at different temperatures by control heating films. The experimental result coincides with vibration analysis in the finite element (FE) method. Variable damping could be achieved by changing the viscoelastic polymer temperature and gear web structure. This research can provide guidance for the polymer material gear damping control in mechanical transmission applications.