Self-cleaning coatings, with benefits to environment, energy and labor saving, have attracted great attention due to their potential application in many aspects of human's daily life. In this perspective article, the recent efforts to understand and improve photo-induced hydrophilicity and self-cleaning properties of TiO2 are reviewed. Particular attention is paid to the fundamental aspects and mechanism of the photo-induced hydrophilicity effect. The challenges that need to be addressed over the coming years to improve the efficiency and extend the application are also presented.