Hydrogenated amorphous carbon (a-C:H) films were deposited on aluminium alloy substrates by microwave electron cyclotron resonance chemical vapor deposition(ECR-PECVD) at different substrate pulse bias voltage. In order to enhance the interface bonding strength between the film and Al alloy substrate, a 50nm silicon film was firstly fabricated on aluminium alloy substrate by unbalanced magnetron sputtering. The fiction and wear properties of the a-C:H films were evaluated using a ball-on-disk tribometer in air at room temperature. The results showed that the tribological properties of the a-C:H films decreased with the substrate bias voltage increased from -150 to -1000V. The a-C:H films deposited at -150V bias voltage had the best wear resistance.