The characteristics of gonadal structure,gamete(sperm and egg)morphology and embryonic development of Hyriopsis schlegeli were studied by continuous observation and in vitro culture.The results showed that the absolute fecundity was 1.93×10⁴-1.03×10⁵ eggs and the relative fecundity was(2.25±1.09)×10³ eggs/g.The gonad index(GI)was 24.09%±0.33%.The embryo cultured in vitro could develop successfully to blastocyst in nutrient solution prepared by ourselves.Embryonic development and process were described.The embryo development of H.schlegeli was divided into four stages:cleavage,blastocyst,gastrulae and glochidia.The embryonic development took 12 days when the water temperature ranged between 18-23℃.The optimum temperature range for the embryonic development was 20-30℃.As observed,the glochidia of this species were hooked and there were relations between embryonic development stages and the outer gill characters of the female.Our results will provide valuable data for artificial reproduction,germplasm resource conservation and breeding in freshwater pearl mussel.