Abstarct: When fuel is stored in the tank, the epoxy glass fiber reinforced tank loses its mechanical properties after a while due to fuel absorption. With the expansion of nanotechnology, nanostructures can be used in the composition of composite materials. In this study, by adding 0.5% by weight of silica nanoparticles to the matrix material, which was made by manual laxyering method (6 laxyers), and an ultrasonic device was used to homogenize the nanoparticles with epoxy, for debubbling in the homogeneous mixture of silica nanoparticles / epoxy, an oven and an autoclave were used to manufacture a nanocomposite plate that creates a vacuum. The samples were subjected to tensile, bending, vibration, fuel absorption and scanning electron tests; then, the results of the tensile, bending and vibration tests before and after immersion in fuel were examined. Before immersion in fuel, by adding nanoparticles to the matrix, the tensile strength and elastic modulus were improved by 12.91 and 3.42 percent, respectively. Improvements in these properties were also observed for samples immersed in fuel by adding nanoparticles. In the bending test before immersion in fuel, by adding nanoparticles to the matrix, the bending strength increased by 26.5 percent and the natural frequency increased by about 1.75 percent; while the bending modulus decreased due to embrittlement of the samples. Scanning electron microscopy showed that the void space in the glass-epoxy composite was much larger than in the nanocomposite and that the nanocomposite sample was denser.