The activities of CAT and SOD and the effects of the activities of CAT and SOD under the different conditions of NH3-N in internal sac of Haliotis diversicolor supertexta were investigated. The results showed that the activities of CAT and SOD were different in the varying concentrations of NH3-N,and the activities of CAT declined with the increasing of the concentrations of NH3-N. When the concentrations of NH3-N was 1-4 mg/L, the activity of CAT was higher than that of the control group, and when 5-6 mg/L, the activity of CAT was lower than that of the control group, on the other hand, when the concentrations of NH3-N was 1-4 mg/L, the activities of SOD increased with the increasing of the concentrations of NH3-N, and when 4mg/L, the activities of SOD were maximum, and when 5 - 6mg/L, the activities of SOD declined. The activities of CAT and SOD of abalone also were affected by the concentrations of NH3-N at the different temperatures.