Objective To evaluate the significance of helical CT virtual endoscopy in nasal endoscopic optic nerve decompression for locating the optic nerve canal.Methods It was a retrospective case series study.45 patients (38 males,7 females) undergo the nasal endoscopic optic nerve decompression in the affiliated eye hospital of Wenzhou Medical College between October 2009 and March 2011 were collected.The average age of patients was 32.8±15.1 (9-67 years).Sinus cavity of all patients were reconstructed by helical CT virtual endoscopy and the data were compared with the results of operations.Results Sinus cavity and the locating mark of optic nerve reconstructed by helical CT virtual endoscopy accorded with the the results of operations in all patients,except 4 patients with optic canal comminuted fractures.Sphenoid sinus crest bone were found in 8 ptients (19.51％) and the opticocarotid recess were found in 35 patients (85.37％) which were wally reconstructed by helical CT virtual endoscopy,and were confirmated in operations.Conclusion Sinus cavity and the locating mark of optic nerve can be wally reconstructed by helical CT virtual endoscopy,which can provide a visual,clarity image for operator.