Abstract: In order to study the development and characteristics of larval, juvenile and young Siganus oramin, we analyzed the morphology of early development stage of S.oramin and described the morphological characteristics and ecological habits of different periods in detail. According to the change of the yolk sac and oil ball, oral fissure, fin membrane and spine, pigment and scales of the fish, the post embryonic development of S.oramin was divided into stages of early larva and late larva, juvenile and young fish. The total length of newly hatched larva was (1.913±0.105) mm. The larva started to feed on 3 dah at water temperature of 23−24.3 ℃. On 6 dah, the yolk sac and oil ball of the larva were absorbed and disappeared, then the larva developed into late larvae stage. On 17 dah, the fin membrane of the fish disappeared and the development of the fins basically completed, then the fish developed into juvenile stage. On 33 dah, the whole body of the fish was covered with scales, completing metamorphosis and developing into young fish stage. The growth of larval, juvenile and young S.oramin showed a trend of rapid-slow-rapid trend with age. The 2^nd dorsal fin spine and the pelvic fin spine continued to elongate with age, and reached the maximum on 28 dah then gradually contracted.