The purpose of this study was to examine how Sebastes schlegelii responded to acute pH stress in terms of group behavior and physiological variations. The pH of the water column is lowered during industrial aquaculture due to the high shellfish mortality, excessive algae cultivation, and seawater red tides. Water’s pH rises as a result of the massive consumption of carbon dioxide in the water caused by photosynthesis. Numerous enzymes, including those involved in immunology, antioxidant, and metabolism in aquatic organisms, are impacted by pH variations. Under stress, fish frequently run, reduce their metabolism, and increase the activity of related enzymes such as SOD and CAT. When fish are subjected to external stimuli, physiological and biochemical indices can represent their overall health ability to adapt to their environment. In this study, the effects of acute pH stress on the immunity, liver function, antioxidant activity, and group behavior of juvenile S. schlegelii were investigated. Different pH values (pH 6.5, pH 7.5, pH 8.5, and pH 9.5) in seawater were studied to identify the effects of pH stress on immunity, liver function, antioxidant activity, and group behavior of juvenile S. schlegelii, The results show that S. schlegelii CAT activity significantly increased in the pH 7.5 and pH 9.5 experimental groups at 48 h (P＜0.05), SOD enzyme activity increased significantly (P＜0.05) at 72 h compared to 24 h in all experimental groups and started to decrease after 72 h. ACP activity showed a gradual decrease in the pH 6.5 and pH 9.5 experimental groups, with a rebound in the pH 9.5 experimental group at 96 h but the change was not significant (P＞0.05). At 48 h, AKP fell dramatically in the pH 6.5 and pH 9.5 experiment groups (P＜0.05), but rebounded somewhat in the pH 6.5 group at 72 h (P＞0.05). GPT decreased and then increased in all experimental groups with a significant drop in the pH 6.5 group after 24 h (P＜0.05). There was no significant difference among the pH 7.5 experiment groups (P＞0.05). Throughout the 48 h–72 h period, GOT activity gradually increased in the pH 7.5 and pH 9.5 experimental groups, although it significantly decreased at the start of the 72 h (P＜0.05). In comparison to the control group, S. schlegelii’s degree of aggregation increased greatly and its activity dramatically decreased under pH 6.5 and pH 9.5 (P＜0.05). The results showed that different pH levels influenced S.schlegelii’s physiological processes and behavioral decisions. The immunity of juvenile S.schlegelii was lower in the pH 6.5 and pH 9.5 experimental groups.