This study investigated the effect of using nano CaCO 3 and nano SiO 2 as partial replacement of cement on the mechanical properties, durability and flowability of concrete. Nano materials were added in four different dosages of 1%, 2%, 3% and 4% by weight of cement in concrete mixture. Mechanical properties of hardened concrete (compressive strength, flexural strength and split tensile strength) have been done after 28 days of water curing. Also water absorption test was carrying out for obtaining the durability properties of concrete specimen. slump flow for fresh concrete was measured for all mixes. Binary combination of nanoCaCO 3+ nanoSiO 2 were also studied the combined effect of the nano particles. The results showed that incorporation of nano CaCO 3 and nano SiO 2 particles lead to increase the packing and enhance the mechanical properties and durability of concrete. A significant performance was observed in case of nano silica addition to the concrete in comparing with nano CaCO 3. The results showed that the workability of fresh concrete was decreased by increasing the content of nano particles.