Abstract: The engagement control of an automated transmission’s clutch when the vehicle is starting is studied. Transfer function model between the input speed of transmission and the engagement displacement of the clutch is built up through an analysis on the system of drive of the vehicle. Owing to the existence of uncertainty in the model, a robust control system of transmission input speed is designed using quantitative feedback theory. The simulation study shows that the system gives satisfactory results when the vehicle starts on different gears and loading.