Abstract: To study the effects of spermine on the intestinal development of Cynoglossus semilaevis postlarvae, we selected the subject with initial length of about 2 cm and fed them with microdiets containing 0 (F1), 0.10% (F2), 0.33% (F3) of spermine and live Artemia (F4) for 28 days. The results showed that F4 group exhibited the highest growth and survival rates. The specific growth rate of F2 group was significantly higher than that of F1 and F3 groups (P0.05). The survival rate of F3 group was 60.27%, which was significantly lower than that of other groups (P0.05). At day 14, the alkaline phasphatase relative activities (AP) in the bodies of fish fed with spermine-containing microdiet were significantly higher than that in fish fed with the Artemia (P0.05); there was no significant difference among groups fed with spermine-containg mecrodiets (P0.05). At day 28, the AP of fish fed with 0.10% spermine was significantly higher than other groups (P0.05); no significant difference was found among other groups (P0.05). F2 and F3 groups showed higher leucine aminopeptidase (LAP) specific activities than F1 and F4 groups at day 14 and 28 (P0.05), but there was no significant difference between F2 and F3 (P0.05). F2 group showed the lowest leucine-alanine peptidase (leuala) specific activity at day 14 and 28 (P0.05). The microvilli length of Artemia group was significantly greater than that of the other groups (P0.05). The mucosal layer of Artemia group was apparently but insignificantly hinner than that of F2 group (P0.05). Both the length of microvilli and the thickness of the mucosal layer in F2 were greater than those of F1 and F3 groups (P0.05). These results suggested that 0.10% spermine in microdiet had positive effects on the intestinal development of tongue sole postlarvae.