Recently Nano-technology is considered to be used in many applications and it has received an increasing attention in building materials. More experimental studies are required for understanding the real behavior of modified concrete with Nano-graphene. In this paper, one hundred-eighty tested specimens with different Nano-graphene types and different ratios were tested to study the behaviour of modified concrete specimens containing Nano-particles at various water-cement ratios. The specimens' dimensions were 40 mm 40 mm 160 mm. eighteen tested specimens are control. In the first group, one hundred-eight tested specimens were prepared by adding Graf Pro nano graphene particles with ratios equal to 0.03%, 0.05%, 0.1%, 0.5%, 1% and 2.5% of cement. In the second group, fifty-four specimens were prepared by adding Graf Plus nano graphene particles with ratios equal to 0.25%, 0.50% and 1% of cement. In the third group, fifty-four were prepared by adding Graf Max nano graphene particles with ratios equal to 0.25%, 0.50% and 1% of cement. All these specimens at w/c=0.3,0.4 and 0.5. Comparison between the tested control specimens and results of tested specimens containing Nano-particles was done. The flexural and compression testing were recorded. The results showed that the use of Nano-particles enhances the microstructure of cement mortar by filling the harmful pores and dandifying the microstructure of cement mortar. Finally, the Nano-particles resulted in significant increase in the flexural and compressive strength of cement mortar.