With the development of science and technology, especially modern industry, air and water resources suffer more and more severe pollution. The problem how to effectively protects air and water resources and keeps human health has aroused wide concern. According to recent research, nanometer TiO2 powder own strong oxidation and reduction capability under certain light (UV light, wavelength under 387.5nm) and have no selectivity to organic substances, can finally get rid of environment contamination. Thus for, there have had plenty of reporting about sewage disposal with nanometer TiO2 powder photocatalyst, it can degrade a part of inorganic compound and many kinds of organic compounds, such as phenols, dyestuff, hydrocarbon, surface active agent, organic pigments, halogeno aromatic compound, polynuclear arene, insecticide etc, and mineralize them into the little molecules (CO2 and water) thoroughly. Thus it can be seen, nanometer powder photocatalysis degradation has good prospect as a new technology about decomposing organic compound.