Blood-retina barrier destruction, nerve injury, formation of neovascularization and fibroblast proliferation membrane are important pathological changes of DR, which are related to the combined effects of various vitreous cytokines. VEGF is mainly involved in increasing retinal vascular permeability and inducing neovascularization. Pigment epithelium derived factor is vital reducing vascular permeability and neuroprotection; IL plays a key role in mediating inflammatory response. TNF-α is related to inflammation, which is significantly up-regulated by hypoxia. TGF-β is an important cytokine regulating cell proliferation and differentiation. Connective tissue growth factor can promote the growth, migration and adhesion of endothelial cell. In addition, many other molecular mechanisms have not been fully elucidated, and further study on the molecular mechanism of DR is urgent. With the further study of molecular mechanism, the early intervention and targeted treatment of DR will be more effective.