Chemiluminescence emission was first observed in the interaction of TiO2 nanoparticles with NaOH solution.In the presence of surfactant of CTAB,the riboflavin can enhance the chemiluminescence intsnisty of TiO2 Nanoparticle-NaOH.Based on this,a new chemiluminescence system of TiO2 NPs-NaOH was fabricated,and a novel chemiluminescence method for determination of riboflavin was developed.Various factors affecting the CL emission intensity of the system were investigated.Under the optimum conditions,the linear range for the determination of riboflavin was in the range of 5.0×10-6-3.5×10-4 g/mL,with a detection limit of 3.0×10-6 g/mL.The relative standard deviation(n=11) for the determination of 2.5×10-5 g/mL riboflavin sodium was 2.9%.The method was applied in the determination of riboflavin preparation of tablets,and the results were in good agreement with those obtained by the pharmacopoeia method.The mechanism of the CL reaction was also discussed briefly.