Objective To understand the clinical features and electrophysiological characteristics of familial nanophthalmos. Methods Pedigree clinical research was performed on a family with nanophthalmos. Detailed ocular examinations including visual acuity, fundus ophthalmoscopy, axial length, optical coherence tomography (OCT), pattern visual evoked potential (PVEP), pattern electroretinogram (PERG), and full-field ERG were obtained for each of the family members. Results Three consecutive generations, including five affected subjects were confirmed in this family. Affected subjects occurred in all three consecutive generations, and father to son transmission occurred, which was consistent with autosomal dominant inheritance. The best corrected visual acuity of five patients was lower than 0.8 LogMAR, and axial length of three patients ranged from 17.27 to 18.85 mm with shortening of the anterior chamber and the vitreous cavity. Three patients had a small crowded optic disc, and one had a normal fundus. OCT examination showed normal retinal morphology but increased foveal thickness (>280 µm). Visual electrophysiological tests revealed normal P100 latency and amplitude in the affected subjects. The PERG was normal but both a- and b- wave amplitudes were significantly higher than the age matched normal subjects for full-field ERG. Conclusion The nanophthalmos condition can be inherited in an autosomal dominant pattern. The presenting visual acuity was less than normal for all patients, and the foveal thickness was increased with a supernormal full-field ERG response.