To study the effects of soybean protein isolate (SPI) on growth performance and intestines of juvenile Jian carps (Cyprinus c arpio var.jian), 720 fish with initial body weight of (11.34±0.16) g we re averagely allocated to 5 groups with 3 replications, feeding isonitrogenous d iets with white fish meal protein replaced by 0, 40%, 60%, 80% and 100% SPI prot ein respectively for 9 weeks. The results showed that weight gain, SGR, feed in take, intestine weight, intestine length, height of proximal and distal intestin al folds were significantly decreased while feed coefficient increased at the 60 %-100% substitution (P＜0.05), and it was accompanied by patholo gical disruption of the proximal and distal intestines including sloughing of ep ithelium tip, widening of lamina propria and increasing amounts of leukocytes in it. At the 60%-100% replacement, lysozyme content of middle and distal intestin es increased (P＜0.05) compaired to that of sole fish meal prote in group; while corresponding antibody level was respectively increased (P＜0.05) when 60%-80% and 60% fishmeal protein was replaced, followed by relative significant decrease at higher substitution. It is concluded that SP I has negative effect on growth performance of juvenile Jian carps when compared to white fish meal, and high level dietary SPI suppresses intestine growth and disrupts intestine mucosal. Pathological disruption of intestinal mucosal involv ed changes of intestine nonspecific and specific immune induced by SPI. In a d iet for juvenile Jian carps, SPI can be used to replace 40% of fish meal protein without negative effect on feed utilization.