In order to improve the degradation resistance of sisal fibers in the alkaline cement matrix and enhance the fiber-matrix interface adhesion, silane treatment on fiber was studied. Four kinds of commonly used silane coupling agents were selected to modify the sisal fibers via the simple dip-coating method. Contact angle, water retention, and semi-immersion tests were performed on the sisal fibers to determine the influence of silane treatment on their hydrophilicity and barrier property. The interfacial bonding between the sisal fibers and cement matrix was studied by a self-designed fiber pull-out test. Furthermore, the degradation of sisal fibers embedded in cement matrix and sisal fiber reinforced cementitious composites (SFRCC) was evaluated based on the changes of mechanical properties with accelerated aging. The results indicate that silane treatment is an efficient approach to mitigate the degradation of SFRCC.