Tapered roller bearings are widely used in transmission systems due to their compact design and high load-carrying capacity. However, the transient mechanical characteristics in existing studies are insufficient, and the accuracy of dynamic modeling needs improvement. To address this, a dynamic model for tapered roller bearings is proposed, based on precise contact modeling and an oil film damping model. The transient positional relationship between the different components of the bearing is analyzed using rigid body dynamics theory and spatial coordinate frames. The initial contact force is determined using the Hertzian contact model and slicing method. Next, the effects of elastic flow lubrication and oil film damping are incorporated to obtain the coupled contact damping and oil film friction force in the contact area, achieving an accurate solution for the transient contact force. Based on these considerations, a differential equation describing the bearing dynamics is developed, accounting for the churning losses of the bearing components, and a transient, accurate solution model for tapered roller bearings is established. Comparison with classical static theory and the dynamic models shows that the contact force simulation error of this model is less than 1%. Experimental testing of friction torque in tapered roller bearings at varying rotational speeds confirms that the total friction loss predicted by the simulation is within a 10% error margin. This study also explores the mechanical characteristics, such as contact force and damping, and the dynamic behavior of tapered roller bearings under sudden load changes. Furthermore, it examines how changes in operating conditions affect the contact characteristics in the contact zone. The proposed modeling approach provides a precise and efficient method for calculating the engineering design and predicting the operational performance of tapered roller bearings.