The distribution characteristics of ATPase in phloem and the flesh sink-cells of fruit in different developmental stages of Ziziphus jujuba Mill.cv.Lingwuchangzao were studied by ATPase ultracytochemical location technology.The result showed that:(1)In the first rapid growth of fruit,there were abundant plasmodesmata in the SE-CC complex and its surrounding cells,making the phloem a symplastic integration.There were abundant plasmodesmata in the phloem parenchyma cells,but there were less ATPase sediments in various cells of phloem.(2)In the slower growth period,the distribution of ATPase sediments in various cells of phloem increased gradually.(3)In the second rapid growth of fruit,there were less plasmodesmata between the SE-CC complex and its surrounding parenchyma cells,resulting in the symplastic isolation between them.There were less plasmodesmata in phloem parenchyma cells and the flesh sink-cells,numerous vesicles and membrane bubbles were found in the sieve tube,phloem parenchyma cells and the flesh sink-cells.The ATPase activities were higher in plasma membrane,vacuole membrane,vesicle membrane,cell wall and intercellular space.To sum up,the photoassimilates unloading from sieve tube element was symplast pathway in the first rapid growth of fruit;the symplast pathway and apoplastic pathway existed simultaneously in the slower growth period;the photoassimilates unloading adopted mainly apoplastic pathway in the second rapid growth of fruit.The photoassimilates unloading pathway in phloem existed differences in different developmental stages of fruit.