Abstarct: In this experimental research work we have studied the morphological plus elemental analysis, structural and optical properties of SiO2 nanostructures grown on Si substrate by chemical vapor deposition (CVD) method. In this study, we have used the scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) apparatus. In samples grown by this method, SiO2 nanostructures were synthesized by the pure (99.98%) silicon monoxide (SiO) powder in the presence of Ar as carrier gas. In the first section of this study, the effect of the distance of the substrates - P-Si(111) and P-Si(100) - from the boat, the effect of growth time and also carrier gas flow rate on physical properties of films were investigated. We found substrates are covered with networks of nanowires with various Si to O atomic ratios, and have a polycrystalline nature for closer samples to the boat (~ 4 cm) and amorphous nature for the farther ones (~10 cm). In the second section, the effect of the presence of the catalyst were investigated on synthesize of SiO2 nanostructures. In this experiment we used the SnCl2.2H2O powder as the catalyst and a mixture of Ar and O2 as carrier gas. In this sample, a polycrystalline porous laxyer is grown on silicon wafer.