We studied the micro- and ultramicro- hepatical structure of Oncomelania snails. The results showed that the hepatical glandulous tubes were composed of simple columnar epithelis and cellular polarity was quite strong, cellular organs were well developed, rough endoplasma recticulium distributed around cellular nucleus in the shape of polylayer and platelayer. The shape of mitochondrion had ellipse and rhabditi form, and Golgi's body and lysosome were in the upper of the nucleus. There were four kinds of secretory granules in the cytoplasma granules high electron density in the base of cell, macro granules in the middle, large and small granules which could release into glandulous tube together with cytoplasma near by the free end; skein cells were simillar to triangle and there are blood cells and capillary cave seen in the hepatical interstice.