Abstract:  Choroidal neovascularization (CNV) can be caused by agerelated macular degeneration, pathologic myopia, ocular trauma, and other eye diseases. The pathogenesis of CNV has not been fully elucidated. Cluster of differentiation 40 protein (CD40) and its ligand (CD40L) costimulatory system is an important signal transduction pathway in immune cells, which activates CD40 to stimulate a variety of angiogenic growth factor secretion, such as VEGF, basic fibroblast growth factor, and leads to the CNV. The high level of expression of CD40 and CD40L has been detected in CNV related diseases. Intervention of CD40 signal pathway may become a new target for CNV treatment.