Abstract: Reducing NO_x emission is one of the most critical global environmental problems. At present, the traditional denitrification technology generally has the problems of high reaction temperature, low catalytic efficiency and high cost. Therefore, new photocatalytic NO_x removal technologies such as photocatalytic oxidation and photocatalytic selective reduction have attracted great attention. The research progress in NO_x removal by photocatalytic materials is reviewed from two aspects including photocatalytic oxidation and photocatalytic selective reduction. The types of photocatalytic materials, the removal principle and the factors affecting the removal efficiency are emphasized. Finally, the prospects for future development of photocatalytic materials used for denitrification are presented.