Glaucoma is a group of diseases which can threaten and damage the optic nerve and its visual pathway, leading to visual impairment as a result. Glaucomatous optic neuropathy is a chronic disease accompanied by apoptosis of retinal ganglion cells(RGCs), visual field defect and cupping of optic nerve head. The gold standard in functional glaucoma evaluation is standard automated perimetry(SAP), but it is often limited to the subjective feelings of the patients. Still, visual electrophysiological techniques cannot replace the conventional inspection, but with its rapid development, it has provided a new strategy for the early diagnosis of glaucoma as a supplement because it can show changes in amplitude and latency before visual field defect. Here we review three special electroretinograms and multifocal focal visually evoked potentials in the early diagnosis of glaucoma.