The rapid development of electric drives technology presents new challenges in the domain of vibration and noise suppression within gear trains. Dynamics modeling serves as a crucial method for studying vibration and noise; however, a deficiency exists in adequately considering the interaction between tribology and the dynamics of gear drives in current research endeavors. This article proposes a unified tribo-dynamic approach to facilitate a more realistic and accurate linkage analysis of transient mixed lubrication, friction, flash temperature, stiffness, backlash, and dynamics in gear drives. The TPMD approach is proposed to reduce convergence elapsed time. The meshing stiffness and backlash under transient mixed lubrication are developed and used as additional crucial bridges for the interactions in tribo-dynamic, supplementing the traditional consideration of friction. Gear vibration tests are carried out in both LOA and OLOA directions to validate the accuracy of the proposed model. Comparative analyses with conventional models highlight the advancements of the proposed model. The lubricated meshing stiffness, influenced by the combined effects of dynamics and tribology, exhibits characteristic fluctuations and is significantly lower than the Hertzian meshing stiffness. Tribological characteristics in tribo-dynamic differ notably from quasi-static conditions due to gear vibrations. The proposed tribo-dynamic model reveals higher DTE and vibration in the LOA direction compared to traditional dynamics. The intricate effects of friction, meshing stiffness, and backlash on vibration depend on factors like surface roughness, torque, and rotational speed.