Abstract: Four kinds of growth- related traits, which were body length, total length, body height and body width, were selected to study their effects on body weight of GIFT strain of Nile tilapia under different stocking densities. One way ANOVA was applied to analyze the differences of growth- related traits under different stocking densities. Path analysis was employed to study the importance of all variables. After removing variables without significant differences, the results showed that most of the growth-related traits under the three stocking densities were significantly different (P＜0.01) except body length and the total length under the densities of 18000 fish/hm2 and 22500 fish/hm2 (P＞0.05). Body weight of GIFT strain of Nile tilapia was mostly affected by body length, body width, and total length when the stocking densities were 18000 fish/hm2, 22500 fish/hm2, and 27000 fish/hm2, respectively. So in the regression equations, the variables without significant difference were also removed. They were the trait of total length at the density of 22500 fish /hm2, the trait of body length at the densities of 18000 fish /hm2 and 27000 fish /hm2. To sum up, effects of growthrelated traits on body weight were significantly different under different stocking densities of GIFT strain of Nile tilapia, and should be considered in breeding.