The effects of different variables on the friction coefficient of poly(vinyl alcohol) (PVA) hydrogel and stainless steel ball counterpart were investigated by a ball-on-plate friction and wear tester. Factors included lubrication condition, sliding speed, diameter of stainless steel ball, and load. It is shown that the free water in PVA hydrogel has a good lubrication on the friction counterpart. The friction coefficients have little difference between dry and lubricated conditions during the initial test stage. With the time prolonged, friction coefficient of PVA hydrogel under dry condition sharply increased within a short time. Friction coefficient decreased with increasing sliding speed and diameter of stainless steel ball. The decrease in the friction coefficient in bovine serum was 55.38% while the sliding speed increased from . The friction coefficient increased as the load increased, and the effect was more conspicuous at low load region.