Objective To explore the appl ication of 3D nerve visual ization system in processing 2D imageinformation of human ulnar nerve acquired by series freezing tissue section, staining and scanning. And to draw the 3Danatomical atlas of human ulnar nerve through 3D Nerve visual ization software system. Methods One left ulnar nerve (frommedial fasciculus of brachial plexus to transverse carpal l igament, about 50 cm ) was taken from a fresh donated cadaver. After marked with human hair and embedded in OCT, series freezing tissue sections were made and stained with acetylchol inesterasehistochemically. Series 2D image information was obtained through high resolution scanner. Then the microstructure of ulnar nerve was reconstructed with 3D Nerve visual ization software system. Results Different cross sections of ulnar nerve have different numbers, positions and characters of the internal nerve fibers. The microstructure of ulnar nerve could be observed in magnifying visual field at any cross section after reconstructed in 3D Nerve visual ization soft ware system, which made it possible to track stereo courser of fascicles. Conclusion Reconstructed 3D Nerve visual ization software system shows the whole microstructure of ulnar nerve and the 3D stereo-structure of its internal fascicles, thus provides exact topography atlas for medical teaching and facil itates precise repair of ulnar nerve injury to improve theraputic effect.