Abstract: As long time load-bearing implants such as meniscus and cartilages, the fatigue behavior of poly(vinyl alcohol) (PVA) composite hydrogel in physical environment relates to persistence and stability of the implants. The nano bacterial cellulose (BC) was dispersed evenly into PVA hydrogel matrix to prepare nano BC/PVA composite hydrogels by method of dispersive strengthening. To investigate and evaluate the anti-fatigue property and mechanical stability of composite hydrogels in simulated body fluid (SBF) environments, three methods including compression fatigue process analysis, stiffness variation analysis and dimensional stability analysis before and after fatigue were used.The results show that the nano BC/PVA composite hydrogels have excellent anti-fatigue property in simulated body environments, which can meet the requirements of anti-fatigue property for implant in body. By adding nano BC, the mechanical stability and anti-fatigue property of composite hydrogels are improved effectively, but as the addition of nano BC increasing further, the anti-fatigue property of composite hydrogels is reduced. When the mass ratio of PVA to nano BC is 30:1, the nano BC/PVA composite hydrogels show the least maximum displacement increment (0.002 mm), the minimum change of stiffness (5.41%) and the best dimensional stability before and after fatigue, the deformation amount is merely 0.427 mm, and the fatigue property is the best.