The nano-TiO2 photocatalyst was prepared via sol-gel method, and the crystal structure and surface morphology were characterized by XRD and SEM. The photocatalytic degradation of ammonia-N in aquaculture wastewater was investigated by using nano-TiO2 under UV irradiation. In the experiment, the effect of nano-TiO2 dosage, ammonia-N initial concentration, pH value, H2O2 volume concentration, and reaction time, respectively, on the removal of ammonia-N was investigated. On the basis of the results of these experimental data, an orthogonal array experimental design was used to select more efficient degradation condition. The optimal experimental conditions for photocatalytic degradation of ammonia-N can be stated as follows: when the concentration of ammonia-N was 20 mg/L, nano-TiO2 catalyst dosage was 1.2 g/L, the pH value of solution was 5, H2O2 volume fraction was 4 %, respectively, if the reaction time may last 3 h, the removal rate of ammonia-N was expected to reach 92.10 %.