In this study, the e ect of water-cement ratio on the mechanical properties (compressive, abrasion, tensile, exural strength, and permeability) of nano-silica concrete reinforced with polypropylene bers is evaluated. The specimens contain 4% of nano-silica, 0.30, 0.35, 0.40, 0.45, and 0.50 of water-cement ratios, and 0, 0.10, 0.15, 0.25, and 0.35 percent volumes of polypropylene bers. Other design features remain xed in all concrete samples. The results of the experiments showed that with decreasing the ratio of water to cement from 0.50 to 0.30, all the mechanical properties of the concrete were improved. In addition, the test results showed a signi cant increase in mechanical properties improvement of concrete by using polypropylene bers. Tensile strength, exural strength, and abrasion resistance of concrete increased up to 22%, 40%, and 27%, respectively, for the 28-day age specimens. In addition, a considerable reduction of hydraulic conductivity coe cient to 51% indicates high durability of these types of concrete. Compressive strength showed increment rates of 22%, 15%, and 14% for 7-, 28-, and 90-day age specimens, respectively.