Ovary development and oogenesis are important in fish reproductive biology. It is fundamental to understand the ovary developmental characteristics for the investigation of resources, population structure, artificial breeding, and germplasm conservation. In this study, to understand Eleutheronema tetradactylum ovary development and oogenesis, changes of tissue structure in ovary development and oocyte structure in different phases during oogenesis were observed via tissue section with an H-E staining technique. The results showed that the ovary of E. tetradactylum is a membrane-type one, and is close to the abdominal surface of the middle kidney, and the two ovaries were separated at the front end and fused at the back end, presenting a "Y" shape. Oogenesis was divided into five phases, fewer follicular cells began to appear around the oocytes in medium phase II, monolayer follicular cells were formed in later phase II, monolayer thecal cells were formed in medium phase III. The yolk nucleus began to appear in middle phase II and disappeared in early phase III. The yolk vesicle appeared near the nucleus and cytoplasmic margin in early phase III. The yolk granules began to appear between the yolk vesicles in late phase III, and filled the yolk vesicles in early phase IV, the yolk lamellae was formed in late phase IV. During ovary development, each stage had different oocyte phases. In stage V, the oocyte diameter showed a bimodal distribution, with peaks in the range of 50.00 to 100.00 μm and 300.00 to 350.00 μm, respectively. This indicated that the ovary showed asynchronous development and batch spawning. This research elaborated the reproduction rules and strategies, and enriched E. tetradactylum reproductive biology information, providing necessary theoretical reference for the protection, development, utilization, and improvement of E. tetradactylum artificial breeding techniques.