Abstract: A friction pair of CoCrMo alloy ball and CoCrMo alloy flat was employed to conduct the dual-rotary fretting (DRF) wear tests in bovine serum solution with mass fraction 25wt% and under dry condition, separately. The DRF wear behavior and damage characteristics of the alloy were discussed. The results show that, for the interface of friction pair, the slip occurred easily in serum solution than under dry condition. At partial slip region, Ft/Fn values were low in both lubrication conditions. At mixed region, obvious plastic deformation was found at contact inerface under two lubrication conditions. At slip region, the lubrication effect in serum solution was very obvious, and the wear mechanisms were abrasive and oxidation wear, however, the delamination occurred in dry state as well. Tribo-oxidation occurred at fretting interfaces under two lubrication conditions.