:Based on a brief review of semiconductor photocatalytic mechanism and researches in the past 30 years on TiO2heterogeneous photocatalysis, this paper emphasizes that the natural vanadiferous rutile and its modified products, which have not been investigated by either Chinese or foreign research groups, degrade halogenated organic contaminants. By means of grinding, heating in situ, heating, quenching and electron irradiation, the natural rutile could be modified. The results show that the lattice distortion and defects in the natural rutile are attributed to the fact that part of Ti4+ions are replaced by V5+and other impurity ions such as Fe3+, Cu2+and Zn2+. Grinding rutile samples into powder with the particle size of 70~80μm results in 0.33% increase of their lattice volumes. The lattice volumes distinctly increase by 0.93%~2.13% via heating in situ at 700~1 100℃. On the contrary, quench- ing causes the lattice volumes decrease by 0.01%~0.07%. V5+ions in rutile are modified by heating segregation outwards to the surface, and the corresponding lattice distortion is rehabilitated by the role of reconstruction in certain crystal faces, recrystallization and release of the microstrain. Rutile modified by grinding shows some degree of photocatalystic efficiency in degrading trichloroethylene and tetrachloroethylene and has fair photoactivity. Heating at 1 000℃evidently improves the degradation ratio of rutile for the halohydrocarbons and the rutile quenched at 1 000℃and 1 100℃distinctly shows a higher degradation rate. The rutile modified by electron irradiation, however, has obviously lower degradation ratio for trichloroethylene. Furthermore, through the tentative study of 52 kinds of semiconducting metal oxides and metal sulfide minerals, it is found that, for most metal oxide minerals,the maximal wavelength of the light, which can excite photoelectron, ranges from 249 to 777 nm, corresponding to the visible light, whereas that of metal sulfide minerals is 921 nm, corresponding to the infrared light. Therefore, the photogenerated electron_held pairs could be excited by the visible light. Systemic researches on photocatalysis in minerals can play an unique role in revealing the life process of the earth and the environmental evolution. The researches are very important to the realization of oxidization of organic contaminants, especially the permanent organic contaminants that cannot be degraded by themselves, in the system of the earth ' s surface.