Abstract: In order to research the effect of fiber and fly ash on resistance of polyvinyl alcohol fiber reinforced cementitious composites(PVA fiber/cement composites)to sulfate attack under long-term immersion, the research was done by analyzing morphology change, quality change, volume change, compressive strength and microstructure of the samples tested after several experimental periods. The results of the experiments show that the fiber incorporation with good distribution forming excellent network distribution structure in matrix slows down the erosion rate of PVA fiber/cement composites in sodium sulfate solution, but there is the best content for the fiber incorporation. The fly ash corporation solids PVA fiber/cement composites, and obviously improves resistance of PVA fiber/cement composites to sulfate attack with increasing doping content under mass fraction of 50%.