Abstract: Gives the design and implementation of a test bench system for an automated mechanical transmission(AMT) . The effective inertia of vehicle is calculated by applying a power factor, and an experimental method simulating the road resistance force in segments is proposed. A fly-wheel system is optimally designed to provide mechanical inertia. The load simulation and matching of variable inertia of the AMT combined debugging test bench are achieved.Practical application proved that the design of AMT combined test bench meets the requirements.