The photo-catalytic efficiency and durability of nano-TiO2 photo-catalytic cementitious materials for oxidizing nitrogen dioxide were investigated under simulated sunlight irradiation. The experimental results showed that the photo-catalytic efficiency increased with increase of the content of nano-TiO2. When 15wt% nano-TiO2 was added, the photo-catalytic efficiency was equal to 223% of that of standard cement. When activated carbon was used as the carrier of nano-TiO2, the photo-catalytic efficiency of cementitious nano-TiO2 could be enhanced markedly. For example, the photo-catalytic efficiency could reach to 85.7%, which was as much as 359% of that of standard cement when the contents of activated carbon and nano-TiO2 were both 10wt%. Compared with nano-TiO2 powder, the photo-catalysis durability of cementitious nano-TiO2 supported by activated carbon could be improved clearly for that activated carbon could absorb nitrogen dioxide effectively, which was favored to the photo-oxidation of nano-TiO2 on nitrogen dioxide.