Objective: To study the clinicopathological features, pathogenesis and the main points of diagnosis of the NMDA receptor encephalitis with teratoma. Methods: 1 case of anti-NMDA receptor encephalitis with teratoma of ovary was collected clinical data of patient from Beijing Haidian Hospital in 2014, using immunohistochemical EnVision method and reviewing the pertinent literatures and assembling detailed clinical pathological dates of 11 cases the NMDA receptor encephalitis with teratoma analyze the common pathological characteristics of 12 cases. Results: All 12 cases, 11 youngers, were female who accompanied with abnormal nerve behavior and epileptic seizure, and 6 cases of the teratoid tumors contain the nerve. The antibody of anti-NMDA receptor in cerebrospinal fluid and serum were positive in 11 cases. EEG and MRI detection had no specificities. These patients were treated with tumor resection and immunoglobulin therapy, 9 showed a good prognosis, 1 recovered, and 1 died. Conclusion: Anti-NMDA receptor encephalitis associated with teratoma was autoimmune encephalitis induced by teratoma, which may be related with neural elements. Positive detection of the antibody of anti-NMDA receptor in cerebrospinal fluid and serum can be diagnosed. Early detection and removal of the tumor can help the patient to cure.