Composite repair systems of buried pipeline will be affected by moisture and other factors due to anti-corrosion and construction problems. These environmental factors will reduce the service life of the composite system. In this paper, the performance of composite and interface between composite and steel under the action of water were studied. It was found that the formation of micro-cracks on the surface of composite materials and the hydrolysis of epoxy resin were the important reasons for the Performance degradation. Moreover, the aging properties of composite materials and their interfaces under water immersion were analyzed by residual strength theory, and the life prediction equation of composite materials and interfaces were obtained, which can be useful to the field application of composite repair systems.