n order to survive in nature, organisms must adapt to the important environmental changes of the photoperiod, namely the day night light cycle. This study aims to investigate the response of juvenile Sebastes schlegelii to different photoperiods, five different photoperiod conditions (24 L: 0 D, 16 L: 8 D, 12 L: 12 D, 8 L: 16 D, 0 L: 24 D) were set up to observe the changes in behavior, growth, and physiology of Sebastes schlegelii under different conditions. It was found that under the 8 L:16 D photoperiod condition, the distance between individuals of the Sebastes schlegelii was relatively stable, and the group arrangement was more orderly, while under the 24 L: 0 D and 0 L: 24 D photoperiod conditions, the cohesion and coordination of the Sebastes schlegelii decreased; At the end of the experiment, the body length and weight under 8 L:16 D photoperiod conditions were significantly higher than those under other photoperiod conditions (P<0.05), and the feeding situation was good; Under 24 L:0 D photoperiod conditions, the cortisol concentration and glucose content in the plasma of Sebastes schlegelii were higher than under other experimental groups. Under 16 L: 8 D photoperiod conditions, the activities of aspartate aminotransferase and alanine aminotransferase in the plasma of Sebastes schlegelii showed an increasing trend. The results showed that under the 8 L: 16 D photoperiod conditions, the cohesion and coordination of the fish population were enhanced, making the Sebastes schlegelii more inclined to move in clusters, and also beneficial for its growth and feeding. However, under the 24 L: 0 D and 0 L: 24 D photoperiod conditions, the behavior of the Sebastes schlegelii population was poor, and the 24 L: 0 D and 16 L: 8 D photoperiod conditions were not conducive to the physiological metabolism of the Sebastes schlegelii. In summary, the results of this study aim to provide a reference for optimizing the light environment for the cultivation of Sebastes schlegelii.