To study the photocatalytic of nano-crystalline TiO2 and P/TiO2, nano-TiO2 and P/TiO2 photocatalyst was synthesized by sol-gel process. In the examination, with C2H5OH as solvent, Ti(OBu)4 as precursor and glacial acetic acid as inhibitor. The effect of gelation time by different reaction factors was studied during the examination. The optimum reaction conditions for preparing transparent stable TiO2 gelation are that the temperature is kept at 40°C, the pH value of solution is 2.5，and the molar ration of Ti(OBu) 4:C2H5OH:H2O:CH3COOH is 1:2.5:5:1.5.On this basis, the P/TiO2 composite materials were prepared. The microstructure，morphology and photocatalytic activities of as-prepared nano-TiO2 were studied using X-ray diffraction (XRD) and ultraviolet-visible (UV-vis) spectrophotometer,the photocatalytic efficiency was studied by investigating the photodegradation of methyl orange. Compared with pure nano-TiO2,P/TiO2 had better photocatalytic activities under UV, but little improved under Vis.