The present study investigates the effect of SiO2 nanoparticle on the hydrophobic and mechanical properties of Poly vinyl alcohol (PVA)/ SiO2 nanocomposite fibers. Firstly, nanocomposite fibers based on PVA/ SiO2 were prepared via electrospinning method. Hydrophobic properties of nanocomposite fibers were determined via contact angle measurement instrument. Improvement in hydrophilicity of the polymer-air interface by addition of SiO2 was clearly evident in the observed contact angles of water on PVA/ SiO2 nanocomposite fiber mats. The tensile results show that the Young’s modulus of these nanocomposite fibers were greatly improved in presence of SiO2. At the same time, there was a deterioration in elongation at break and tensile strength of the nanocomposite fibers.