Aerogel is a nano porous material with so low density which is synthesized by sol-gel process. In recent years due to aerogel’s unique properties, several studies have been done on the properties of this material, especially in the field of insulation .The use of aerogel in unsaturated polyester resin, as a resin widely used in various industries and at lower prices with an emphasis on mechanical properties, has been paid very little attention. The use of aerogel as a filler in fiber reinforced composites have been investigated in order to study the mechanical properties. In this study, regarding the lack of research in the field of composites reinforced with basalt fiber. Basalt fiber, which is known as a good reinforcing material with good mechanical and chemical properties when is compared to glass fiber, was used as a reinforcement part. In this study, two hydrophobic and one hydrophilic aerogel with different pore structures and physical properties synthesized. The effect of these variables and different weight percentages of them on mechanical properties of reinforced composites were investigated. The results of the polyester-aerogel nanocomposites showed that the hydrophilic aerogel sample with the presence of only 0.1% by weight of the lead to an increase in toughness (85%) without loss in strength. The increase for hydrophobic sample with fewer surface area was less than 20%. Increasing aerogel weight percentages from 0.1 to 0.3 and 0.5 reduced mechanical properties. The fracture surface of the sample show the mechanism of toughness, separation and the formation of cavities are apparent. The results showed that the presence of basalt fibers in nanocomposites resulted in a negative impact on mechanical properties of nanocomposites. SEM images of the fracture surface of the samples of punching shear test showed that the presence of aerogel weakened the properties of resin and fiber interface, which resulted strength reduction. In this study aerogel fillers was dispersed in resin volumetrically, but they have an impact on the properties of the interface. Keywords: aerogel, basalt fiber, mechanical properties, polyester resin, the fracture surface, toughness