Abstract: Due to the deposition of C on Si target during the deposition process, we can use this target poisoning phenomenon to deposit DLC film with trace or low Si, the Si-DLC films with different structures were prepared via different negative bias application. The structure, cross-sections, composition, mechanical and tribological properties of the films was systemically investigated by XPS, Raman spectra, scanning electron microscopy, nano-indenter and tribo-tester. The results show that the content of sp³ hybrid carbon was increased as the Si doped, and Si-doping could release the internal stress and increase adhesion to silicon substrate. The Si-DLC film prepared at bias of -600 V exhibited higher hardness, higher adhesion, lower friction coefficient about 0.018 and lower wear rate about 1.60×10^-16 m³/(N·m) in the ambient atmosphere.