α-crystallin is the predominant structural protein in the lens. It is a member of small heat shock proteins(sHSPs)which has the common functions of HSPs. It also has anti-apoptotic activity etc. Recently, it has been proved to combine with the cellular membrane of retinal ganglion cells(RGCs)to enhance the survival of RGCs and the regeneration of axons, thereby partly restore visual function. But we haven't come to a unified conclusion of the mechanism. This review is focused on structure and functions of α-crystallin, the protection function and mechanism of α-crystallin towards RGCs after the optic nerve injury.