In this paper, technichques relating to modification of TiO_22 based photocatalysts in recent years such as metal cation doping, metalloid anion doping, ion implantation, photosensitization, fixed technology and so on were reviewed based on the brief introduction of the degradation mechanisms of semiconductor photocatalysts. The recent developments in the preparation of the photocatalytical titania nanoparticles and thin films at low temperature were reviewed with comparation for the different preparation m...