The purposes of this research were to study the effect of nitrogen content levels on structural properties and photocatalytic activities of catalysts with various calcination temperatures and to test the photocatalytic degradation of paraquat under UV and visible light. The results showed that the effect of calcination temperature was significant on physical properties and amount of nitrogen element, but insignificant on phase structure and oxidation state of titanium (Ti) atom. The N-doped TiO2 samples demonstrated only anatase phase because nitrogen dopant in TiO2 restrained the phase transformation from anatase to ruffle and displayed nanorice-like morphology. The bandgap energy was about 3.07-3.18 eV. The nitrogen content was only observed at 100, 300 and 400 degrees C. The nitrogen (N) atom can be incorporated in TiO2 structural lattice with interstitial site. The specific surface area and nitrogen content level showed the important roles for the photodegradation of paraquat under UV and visible light irradiation.