Diamond-like carbon(DLC) films were prepared on silicon (100) wafer by microwave electron cyclotron resonance(MW-ECR) plasma source ion implantation(PSII). Th e results showed that the films had typical properties of DLC. The films was den se and homogeneous, and the roughness and friction coefficient was low. The conn ection between the properties of the films and the flow ratio of hydrogen was cl osely. With the increase of the flow ratio of hydrogen to methane, the depositio n rate and the roughness of the films decreased. The sp3 bond obtaine d was mor e likely diamond like, which had low surface energy, consequently making the fri ction coefficient of the films decrease rapidly.