Siberian sturgeon Acipenser baeri is one of the most popular fresh water aquaculture species in China. Artificial spawning of this species has succeeded. In order to provide information that may help with the improvement of fry rearing techniques, the morphological observation during postembryonic development of Siberian sturgeon Acipenser baeri (F₂) were studied under rearing conditions. Newborn prelarval (0 day age) ［mean ±SD full length (FL) (9.16±0.21) mm］ was conducted till the age of 53 days (87.12±1.92) mm. According to morphological development, postembryonic development of Siberian sturgeon was divided into two different phases, the prelarval stage between hatching (0 day age) and first feeding (9day age ), and the larval stage between the initiation of external feeding and metamorphosis (37day age ). During the prelarval stage, the differentiation and morphological development of respiratory, swimming, sensorial and feeding systems were very intense, while the larval period as characterized by the development of dorsal, lateral and ventral rows of scuta. Morphogenesis and differentiation were more intense during the prelarval than larval and early juvenile stages. Such abrupt changes on growth patterns were related with improvement on respiration, feeding and swimming ability. Rapid development of those functional systems helped larvae escape from predators and get external food efficiently, which contributed to its survival. For the improvement of artificial fry rearing technique, specific conditions should be provided in time which depend on the early life stage growth patterns, so that important organs might have priority to develop normally and survival rate of early life stage might increase.