Abstract: The process of preparing CTS modified TiO2 with Ti(OBu)4 as precursor and C2H5OH as solvent by sol-gel method and its photocatalytic activity were Investigated in this article. The influence of different factors was analysed. The results show that when the volume ratios of water to Ti(OBu)4 , C2H5OH to Ti(OBu)4 and inhibitor to Ti(OBu)4 are 0.57, 1.4 and 0.4 respectively, pH stays between 3～5, tempreture is between 25～35℃, the steady TiO2 sol is obtained which contain anatase crystal TiO2 capable of photocatalysis. The characterization results show that CTS is discomposed absolutely and anatase is obtained. Furthermore, the photocatalytic activity of CTS modified TiO2 has more effective result than which of TiO2 alone. After 60 minutes, concentration removal rate has been proved from 32％ to 48％，and TOC from 14％ to 23％.