By means of histological section and H. E. dyeing, the histological characters were studied in the process of the ovarian development and Oogenesis of Hyriopsis cumingii. The mussels were cultured in the pond which could be used to reproduce. The ovarian development of Hyriopsis cumingii could be divided into five stages: proliferating period in February, growing stage in March, maturing stage started in April, spawning stage during April to November, resting stage during December to January. The oogenesis of Hyriopsis cumingii could be also divided into five stages: oogonia, early vitellogenic oocytes, vitellogenic oocytes, late vitellogcnic oocytes, and mature oocytes. The oocytes matured and spawned in different time. In the early time of oogenesis, the yolk stalk was not observed obviously. A big nucleolus was observed in the middle time of oogenesis, but no small nucleolus was observed.