In order to improve the photocatalytic activity of TiO2, the optimal catalytic conditions of TiO2 and niobate as well as the composite TiO2 and niobate photocatalyst were studied. 10 mg/l of methyl orange solution was taken as imitated waste water. The results indicated that the optimum dosage of TiO2 was 0.8 g/l. The optimal calcination temperature to prepare lanthanum niobate was 900 oC. n(La):n(Nb) was in the range of 0.6:1−3:1, and the photocatalyst prepared in the ratio of 1.4:1 showed the highest activity. The results also showed that, TiO2-lanthanum niobate composite prepared by solid-state reaction method showed better photocatalytic activity on methyl orange degradation compared with pure TiO2. After 120 minutes of irradiation, methyl orange degradation rate reached 94.2 % when using the composite photocatalyst.