Abstract: Glass fiber reinforced monomer casting nylon composites have been prepared by anionic polymerization of caprolactam(GFMCPA).The friction and wear behavior of composites with different proportion of glass fiber under dry condition or water lubrication were investigated through a ring-black wear tester.The tribological properties of composites were significantly affected by the proportion of glass fiber.The higher wear resistance of the composite can be attained when the proportion of glass fiber reach 30%.Compared with dry friction,the friction coefficient and wear loss of composites greatly decreased under water lubrication.The main wear mechanism of composites with low proportion of glass fiber was adhesive and abrasive wear while that is abrasive and fatigue with high proportion of glass fiber.