Schlemm canal is an important part of the aqueous humor outflow pathway and a circular canal around the angle of anterior chamber.Its inner wall was separated by a layer of endothelial cells with trabecular meshwork, and its outer wall was drained by 25-30 collector channels.At present, it is considered that Schlemm canal is the main part of resistance to aqueous humor outflow and plays a vital role in the regulation of intraocular pressure.The collapse of Schlemm canal will cause the increase of intraocular pressure, which will lead to the damage of fundus oculi and the occurrence of glaucoma.With the development of minimally invasive glaucoma surgeries, Schlemm canal has become a significant part in anti-glaucoma surgery.Therefore, the morphological observation of Schlemm canal is particularly important.With the development of imaging technology, mainly ultrasound biomicroscope and optical coherence tomography, the study on the morphology of Schlemm canal has developed from the initial histological study of isolated eye by light microscope and electron microscope in vitro to the imaging observation in vivo.In this review, the morphology and physiological function of Schlemm canal in aqueous humor outflow pathway and the biometrics of its morphology were described.