Abstract: Using conventional histological methods and scanning electron microscope，the developing process of oocytes and the morphological structure of the mature eggs of Gobio cynocephalus were observed. The results showed that Dybowsky egg development process was divided into six phases. In Phase Ⅰ the oocytes were primarily composed of undifferentiation oogonia, and in phaseⅡ the oocytes were surrounded by a layer of follicular cells. Phase Ⅲ and Ⅳ oocytes differentiated significantly, with accumulated vitelline vacuoles from plasmalemma to karyolemma and yolk from karyolemma to plasmalemma. Phase Ⅴ oocyte was the mature egg, with rich yolk and less vitelline vacuoles in the cytoplasm，and the Phase Ⅵ oocytes, if not released, entered the degradation stage, with damaged membranes and the yolk reabsorption. The micropyle shaped like a funnel, the type of micropyle area belongs to down spin hybrid system. The special structure named cylinder was full of the mature egg surface, the height of cylinder is 18.3~30.6um, the average density was about 0.15/um2, maybe the fishes with the similar ecological type like Dybowsky have this egg envolpe structure characteristics, we conjecture that it plays a significant role in fertilized egg hatching and embryonic development.