Concrete is the most common material in construction of the hydraulic structures. Dams and the related hydraulic structures are known as long servicing life structures. Their maintenance costs are high thereby their durability is an important issue. Concrete abrasion is one of the most important factors in threatening the durability of hydraulic structures, thus is considered as a primary factor in determination of the servicing life of a hydraulic structure. Concrete abrasion is generally caused by friction and impact of suspended particles such as; sand, gravel, rock, ice and debris. Spillway aprons, stilling basins, sluiceways, culverts and tunnels are vulnerable structures to the concrete abrasion. Former studies have focused on improving the mechanical properties of concrete using different additives and have reported success in their concrete design mixtures. Recently, among different additives, investigators increasingly notice the nano additives. For this purpose, part of the cement in mixture is replaced by nano materials. Former results indicate that nano particles improve the mechanical properties of concrete remarkably. Present study focuses on investigating the effects of nano silica on durability of concrete in hydraulic structures. Experimental study was perfomed on durability of ordinary and self-compacting concrete (SCC) including abrasion resistance, permeability and water absorption containing nano-solica. According to the merits of SCC, it is widely used in hydraulic structures such as; dams, spillways and tunnels, thus this was the main motivation to apply nano silica in SCC as the major focus of the present study. Based on the results, the effects of nano-particles on mechanical and durability aspects of ordinary and self-compacting concrete were compared. Consequently, the optimal amount of silica nano-particles in design mixture for both ordinary and self-compacting concrete was obtained. To achieve a proper concrete mixture, the time and technique of the mixing materials in SCC especially by adding the nano-particles are important issues. Adding nano-silica into the mixture of water and superplasticizer, as well as using high shear disperse mixers lead to a homogeneous mixture of nano-silica in concrete (ordinary concrete and SCC). Results of fresh-phase concrete tests indicated that viscosity and shear stress increased. Thus, the workability and bleeding of the concrete mixture decreased. Mechanical and physical characteristics of the concrete specimens including compressive strength, abrasion resistance, permeability and water absorption improved by means of adding a low percentage of silica nano-particles significantly. However, greater values of nano-silica weakened the concrete expected properties. Negative effects of excessive magnituds of silica nano-particles in self-compacting concrete were more evident compared to the ordinary concrete.The results of compressive strength tests have a logical correlation with the results of abrasion resistance tests. Therefore, a second order polynomial correlation was developed between the 28-day compressive strength and abrasion resistance of concrete. Keyword : Durability, Hydraulic structures, Nano-silica, Self-compacting concrete, Abrasion resistance, Permeability, Water absorption