The present paper is a laboratory study on the effect of using silica nanoparticles with cellulose fibers in increasing compressive, flexural and tensile strength of concrete and the results has been compared with ordinary concrete made of cement alone. Evaluation is conducted based on a 28-day long period, and a 7-day short period; the results showed that the concrete containing a small percentage of nanoparticles, with a determined ratio of water and cement, in comparison with ordinary concrete with the same water and cement ratio, has improved considerably. For comparison, compressive, flexural and tensile strength of plain concrete and the concrete containing cellulose fibers is also measured. The results show that by each of these three criteria, strength of concrete containing nano-materials and the cellulosic fibers has been increased considerably. Finally, the relationship between compressive, flexural and tensile strength of concrete shows that the tensile and flexural strength of the concrete containing nanoparticles increases by increasing compressive strength.