Tumor immunotherapy includes immune checkpoint inhibitor (ICI), tumor vaccines, and adoptive cell therapy. Immunotherapy, as the main systemic treatment for advanced malignant tumors, kills tumor cells by activating the immune system and prolongs the survival of patients. However, excessive immune responses can cause immune-related adverse events (irAE), causing damage to systemic tissues. ICI are the main tumor immunotherapy drugs that cause optic nerve irAE. The most common optic nerve irAE are optic neuritis, only a few patients appeared arteritic anterior ischemic optic neuropathy. Sudden painless loss of bilateral vision is the most common clinical manifestation. In severe cases, the vision decrease to no light perception. Early diagnosis and early adequate glucocorticoid treatment can improve the symptoms. Therefore, neuro-ophthalmologists and oncologists should know the clinical characteristics of optic nerve irAE, in order to diagnose and treat early and improve the prognosis.