Objective To observe the ultrastructure of Taenia solium oncospheres. Methods Patients infected with Taenia solium were de-wormed by decoction arecae and pumpkin seeds to get the mature proglottids and collect eggs. The eggs were treated with sodium hypochlorite to break the eggshells. Oncospheres were collected in Percoll （iso-osmotic solution）, and activated with artificial intestinal juice. The specimens were prepared with hot agar centrifugation for ultra-thin sections and observed with transmission electron microscopy（TEM）. Results T. solium oncosphere was in oval shape with a size of （14-17）μm ×（10-13）μm. There were some irregular ecphymata or plicae on its surface. The hooks were composed of outer pellet layer, the middle fibrous layer and the central core marrow. Myoblasts, hook-forming cells and cerebral cortex cells were observed in the mature oncospheres. Conclusion The ultrastructure of Taenia solium oncosphere is similar to that of Hymenolepis diminuta, with difference in hooks. There are binucleate cells which play a role in forming epithelium in the development of oncospheres.