TiO2 nanopowder, loaded with SiO2 and Cu-SiO2, was prepared under both acidic and basic environments via the hydrothermal method. The morphology and structure of TiO2 were studied by XRD, TEM, and FT-IR. The photocatalytic activity of samples was studied by monitoring the degradation of methyl orange, using a UV-visible spectrophotometer. The effect of Ti/Si ratio, pH, and Cu2+ addition on the formation of TiO2 and its photocatalytic activity was investigated in detail. The results show that a large surface area and a high surface acidity were important factors to achieve good TiO2 performance. The presence of Ti-O-Si bonding enhanced surface acidity, which improved its ability to adsorb more hydroxyl radicals and increased its surface area. The addition of 0.1 mol% concentration of Cu2+ and 25 mol% SiO2 in TiO2 induced the formation of new states close to the conduction band, which narrowed the band gap energy and enhanced the photodegradation efficiency.