Abstract: An oscillator-type tribometer was used to determine the friction factor of lubricated sliding pairs made of poly (vinyl alcohol) hydrogel/poly (vinyl alcohol) hydrogel and human articular cartilage/poly (vinyl alcohol) hydrogel respectively, and the research of the lubricating mechanism was carried out according to Stribeck curves. The experimental results show that when the hyaluronic acid (HA) is used as an artificial synovial fluid, poly (vinyl alcohol) has similar frictional characteristics with human articular cartilage and the friction factor of poly (vinyl alcohol) hydrogel/poly (vinyl alcohol) hydrogel is smaller than that of human articular cartilage/poly (vinyl alcohol) hydrogel. It is concluded that the two lubricating mechanisms are both liquid film lubricate.