Abstract: In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel with the main linac. The beam dynamics of the Drive Beam injector complex has been studied in detail and optimized. The model consists of a thermionic gun, the bunching system which followed by some accelerating structures and a magnetic chicane. The bunching system contains three travelling wave sub-harmonic bunchers, a prebuncher and a tapered travelling wave buncher all embedded in a solenoidal magnetic field. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimizing the overall bunching process and in particular decreasing the satellite population and the beam loss in magnetic chicane and in transverse plane limiting the beam emittance growth.