Objective　To provide anatomical  basis for performing the transsphenoidal endoscopic optic nerve decompression.　Methods　Twelve heads of adult cadavers were dissected under the operative endoscopy imitating the trassphnoidal approach to observe the optic canal and its surrounding structures. Then the optic canals were removed and sheath was exposed in order to observe the optic nerve and ophthalmic artery.     Results　Optic canal protuberance is a relatively consistent anatomical landmark in sphenoid sinus and the orbital aperture could be determined through the optic canal protuberance. Ophthalmic artery is always located in the ventromedial side of optic nerve and incision of sheath of optic nerve should be performed in the superolateral position.　Conclusions　Optic canal protuberance is an important anatomic landmark; incision of sheath of optic nerve should be performed in the the superolateral position.