Abstract: <SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">Nanotitania has excellent characteristics,such as photocatalytic activity,photoelectric conversion,and photoluminescence.Nanotitania prepared by hydrothermal method has unique advantages.Three crystal structures of nanotitania,mechanism of hydrothermal preparation process,and effects of reaction conditions (raw materials,temperature,and pH etc.) on products were emphatically introduced.By appropriately controlling reaction conditions,the nanotitania with a certain crystal form,size,and shape could be obtained.Photocatalytic mechanism of nanotitania,influence of crystal structures on the photocatalytic activity as well as improvement of photocatalytic properties were also presented.On the basis of photocatalytic mechanism,nanotitania with good dispersion,small grain size,high specific surface area,and controllable crystal form can be designed and produced,which will have vast application value and development prospect in antibacterial disinfection,sewage treatment,and so on.</SPAN>