The blood-labyrinth barrier (BLB) in the stria vascularis is a specially differentiated capillary network that controls the entry of substances from capillaries into the endolymph. This article details the histological structure of BLB, the mechanism of maintaining the stability of endolymphatic components, and its role in the pathogenesis of some sensorineural hearing loss. The pathogenesis and prevention of sexual deafness provide new ideas.