Abstract：Nano—particles，diferent iron content in the iron and nitrogen codoped TiO2 were prepared by sol—gel method with C16H36O4Ti as raw materials，and fluorescence spectrum was used to study the structural characterization． The catalyses in the ultraviolet irradiation effects on the degradation of malachite green was studied，the influence of different impure TiO2，diferent iron codoped TiO2，dosage of the activators and concentration of malachite green were compared．The results indicated that when the Fe／T molar ration of 0．9％ and the dosage is 2 g／L．the photo catalytic degradation of malachite green is the best．The best concentration for degradation of malachite green is 50 mg／L，the rate in 150 min can reach 98．96％ ．And the fluorescence spectrum showed that the less fluorescence intensity，the better catalytic efect of the specimen．