Hybrid special vehicles demonstrate outstanding performance in power and economy, and have become a significant development direction for special vehicles. Due to their complex transmission system structure, variable operating conditions, and high power input, they are prone to local torque overloading and adverse vibrations, which can affect the system’s operational reliability and crew comfort. To ensure that no local torque overloading and subsequent system failures occur during operation, this paper first analyzes the structural principles of the powertrain system for a new type of hybrid special-purpose vehicle equipped with a ten-cylinder engine. A multi-degree-of-freedom torsional vibration model of the powertrain system is established, and the model’s state parameters are simulated and solved to obtain the torsional stresses of each component of the transmission system, thereby conducting verification and optimization. Finally, an analysis of the vibration characteristics is conducted based on the powertrain model, providing strong theoretical support for the active vibration control of the powertrain system.