The aim of the paper was to investigate the tribological behavior of DLC coating under different working conditions. The DLC coating doped with Cr element was deposited on the CoCrMo alloy by magnetron sputtering. The chemical composition of DLC coating was analyzed by X-ray diffraction energy spectrum and Raman spectrum. The surface morphology of DLC coating was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). The tribological properties of DLC coating under different working conditions were studied with a tribo-tester. Results showed that the surface of DLC coating presented granular structure and the roughness value was about 10 nm. Phase analysis showed that the DLC coating had amorphous structure. The average friction coefficient of DLC/CoCrMo tribo-pair was about 0.08 with the lubrication of BSA and NaCl solution respectively, and there were a few scratches on the wear area. Under the condition of dry friction, the curve of the friction coefficient showed a change trend from high to low, and the average friction coefficient was about 0.21. Meanwhile, the graphitization transfer layer could be seen on the worn surface of the pin. When the contact pressure was 1 MPa, the average COF was about 0.10. When the contact pressure increased to 8 MPa, the average COF was about 0.08. Conclusion stated that the suspended bond on the surface of DLC coating is passivated under the condition of lubrication, which reduces the interaction force between DLC coating and the mating surface. The COF is thus low. Under dry friction, the graphitization transfer layer acts as a solid lubrication layer which leads to the decrease of COF. DLC coating has an obvious antifriction effect on the friction pair.