Research Objective: For MT vehicles, gearbox rattle is a common NVH problem which influences the comfort level of vehicle. In order to prevent rattle in the design phase of vehicle, this work aimed to study the excitation mechanism and influence factors of gearbox rattle, and then to propose effective measures. Methodology: First, the root cause of gearbox rattle problem was studied with the aid of classical dynamical theories. And then the simulation model of vehicle powertrain system was built via Matlab-Simulink. Then some critical parameters of the model and some experiential optimum proposals were selected to perform a sensitivity analysis on the torsional vibration, which is the root cause of rattle. Referring the simulation results, the dual-mass flywheel was selected as the most effective solution to gearbox rattle. Results: The simulation results indicated the critical parameters for optimization to prevent gearbox rattle problem in the design phase of the vehicle. And both of the simulation and practical test indicated that, the gearbox rattle could be improved by applying the dual-mass fly wheel. Conclusion: This paper introduced the characteristics and mechanisms of the gearbox rattle problem of a vehicle during its development phase. After performing parametrical optimization and sensitivity analysis via Simulink simulation on the vehicle driveline system, the dual-mass flywheel was selected as the most effective solution to gearbox rattle. This solution was verified through the real vehicle test.