Abstract: In this paper, the effects of ammonia-N (NH₄-N) stress on the activities of lysozgme and three digestive enzymes of Babylonia areolata were studied to reveal its physiological changes. The results show that both the concentration and treatment time of NH₄-N had a significant effect on the activities of digestive enzymes of B. areolata (P<0.05). Compared with the control group: 1) As the treatment time of NH₄-N increased, the lysozyme generally demonstrated a suppression-induction trend. 2) The lower concentration of NH₄-N (22 mg·L^–1) showed an induction-suppression trend to the pepsin activity, while the other concentrations generally showed a suppression-induction trend. 3) The lipase activity of B. areolata was generally suppressed or similar with that of the control group with the prolongation of treatment time. 4) The NH₄-N treatment time affected the amylase activity significantly, but in the case of short treatment time, the lysozgme activities of treatment groups did not have much induction or suppression. In conclusion, the stress of ammonia-N can influence the activities of these four digestive enzymes of B. areolata.