Abstract: A gradient interlayer was deposited on stainless steel disk and silicon wafer by RF-CVD assisted sputtering and reactive sputtering method. Sequentially, a Si-DLC film was deposited on the interlayer by RF-CVD. The effect of the interlayer on the characteristics and tribological behaviors in water of the film was investigated. The results show that the presence of the gradient interlayer increased the content of sp³ carbons as well as the hardness and the Young's Modulus of Si-DLC slightly. The Si-DLC film with gradient interlayer showed higher failure-resistant capability comparing with the film without gradient interlayer.