Abstract: The hatching gland of the grass carp was unicellular and originated from theectoderm. The hatching gland cell (HGCs) were maiuly located in the head end in thejoint region between head and yolk sac, especially in the ventral below the eyes.The period of forming and secreting of the enzyme showed a pattern of some regularities,and could be divided into five stages: pr-formation stage, movable stage, secretory stage, degenarative stage and disappearing stage. The deformed embryo had little differentiation of HGC or with incomplete differentiation.