TiO2 composite oxide nanocrystals were prepared by a chemical co-precipitation method with Al2O3 as heterogeneous composite agent and TiCl4 as starting materials. The influences of the heterogeneous composite agent on TiO2 phase transition process, particles growth and optical absorbance in UV and visible region were studied in detail, and the composite structure was elementarily concluded. The results show that after compounded by Al2O3, the phase transition process and particles growth of TiO2 oxcide nanocrystal are restrained notablely. TiO2 composite oxide nanocrystals are with anatase structure entirely after calcined at 900 degrees C, and well mixed crystalline structure in the range of 950 similar to 1050 degrees C, and the particles after calcined at 950 degrees C are spherical, average diameter 20 similar to 30nm, dispersed equably, and have no reuniting phenomenon, and have the super optical absorbance in UV-Vis region than TiO2 nanocrystal after calcined at 700 degrees C.
