The key factors that directly affect the grading efficiency of live fish are the behaviors of fish shuttling through the grille and congregating on one side of grille after shuttle. An experimental platform consisting of glass tank, LED lamps, camera and computer was designed, and videos of Acanthopagrus schlegeli behavior were analyzed by Matlab, the purpose of which was to study the effects of graded grille on the behavior of Acanthopagrus schlegeli and the preference of Acanthopagrus schlegeli for grille colors, materials and light colors, and test the effects of grille and light combination on the shuttle and congregation behavior of Acanthopagrus schlegeli. The results showed that the presence of grilles significantly inhibited the swimming of Acanthopagrus schlegeli in the tank, and Acanthopagrus schlegeli did not show a preference for shuttling through the grilles; the grille colors further inhibited the activity of Acanthopagrus schlegeli to shuttle through the grilles, and Acanthopagrus schlegeli is more repulsive to red and blue grilles and less repulsive to green and colorless transparent grilles; Acanthopagrus schlegeli is most repulsive to silver steel grilles and least repulsive to transparent PMMA grilles; Acanthopagrus schlegeli has high phototaxis to blue light and strong photophobism to red light. In the design of grille grading system of Acanthopagrus schlegeli, the light-triggered self-grading technology can be introduced, and blue and red light can be set on both sides of the grille, which is conducive to achieving rapid and stable grading. The results can provide some references for the research and development of fish classification equipment and auxiliary facilities..