To reveal the acute toxicity and physiological changes of Babylonia areolata in response to low pH and high pH stress, the pH =8.0 control group and pH =5.0, 6.0, 7.0, and 9.0 were used as the experimental group to investigate the activities of four immune enzymes glutathione peroxidase (GSH-PX), catalase (CAT), peroxidase (POD) and acid phosphatase (ACP) in the body of the Babylonia areolata. The results of the experiment show that pH stress has a significant effect on immune enzyme activity at different times (P＜0.05), while different pH stresses have no significant effect on immune enzyme activity (P＞0.05). After pH acute stress, 1) after 6h of low pH and high pH water culture, there is a decrease in vitality and slow climbing, and death begins to appear after 48h; 2) The activity of GSH-PX in each experimental group shows a trend of "inhibition-induction"; 3) with the continuous extension of time, the CAT activity of each pH treatment group shows a trend of "induction-inhibition-induction"; 4) the POD activity generally show a trend of "induction-inhibition";5)the ACP activity of the low
pH treatment group (pH= 5.0, 6.0) show a trend of "induction-inhibition". This study has practical significance for the cultivation of Babylonia areolata, and also enriches the basic data on the immune performance of other shellfish.