Abstract: We investigated the effects of dietary isoleucine on the digestive enzymes and immune index of juvenile golden pompano, Trachinotus ovatus. Six diets with different concentrations of L-isoleucine (13.2 g · kg^-1, 15.7 g · kg^-1, 18.2 g · kg^-1, 20.7 g ·kg^-1, 23.2 g · kg^-1 and 25.7 g · kg^-1 dry diet) were formulated to contain 430 g · kg^-1 crude protein with fish meal, soybean meal, peanut meal and pre-coated crystalline amino acids. Each diet was randomly assigned to triplicate treatments of 20 fish initial body weight was (6.36±0.03)g for eight weeks. The intestinal amylase and pepsase activities, serum T-AOC and LZM activities, IgM concentrations increased with increasing isoleucine concentration up to 18.2 g · kg^-1, whereas decreased in the groups exceeding 20.7 g · kg^-1isoleucine significantly. Those parameters of the fish fed with diets of 15.7 g · kg^-1and 23.2 g · kg^-1isoleucine were significantly higher than those fed with diets of 13.2 g · kg^-1and 25.7 g · kg^-1isoleucine, while significantly lower than groups containing 18.2 g · kg^-1and 20.7 g · kg^-1isoleucine. There is an opposite change trend in serum urea and MDA concentration, i.e., significantly lower in 18.2 g · kg^-1and 20.7 g · kg^-1isoleucine groups than those in the other groups. The SOD activity rate increased with increasing isoleucine concentration up to 18.2 g · kg^-1, and there was no significant difference when the dietary isoleucine exceeded 18.2 g · kg^-1. So diet with 18.2~20.7 g · kg^-1isoleucine can improve the digestive performance and immune function of T.ovatus.