Patients who have a cerebrospinal fluid cavity that is connected to the extracranial area and have a cerebrospinal fluid leak are called cerebrospinal fluid leaks. The clinical diagnosis of cerebrospinal fluid leakage needs to be based on symptoms, physical examination, combined with some auxiliary tests. I. Symptoms and physical examination: Patients may have symptoms such as loss of smell, hearing loss, blindness, facial palsy, etc. Fluid, usually non-mucus fluid, may flow from the nose, eyes, posterior pharyngeal wall and ears. According to the patient’s clinical manifestations and physician’s examination, cerebrospinal fluid leakage can be initially determined. Second, clinical auxiliary examinations: 1, head CT: when cerebrospinal fluid leakage occurs, head CT can see that the patient has intracranial pneumonia and brain damage; 2, quantitative glucose analysis: when the patient has cerebrospinal fluid leakage, fluid will flow from the ears, eyes, nose and other parts of the body, at this time, samples should be taken for examination. If the test result is above 1.7 mmol/L or 30 mg/dl, it can be basically determined as cerebrospinal fluid; 3, nasal endoscopy: it is often used for the localization and diagnosis of cerebrospinal fluid nasal leakage, and if there is a lot of cerebrospinal fluid leakage, clear fluid is seen pulsating out from a certain location; 4, other: if the hospital has advanced equipment, 3D skull base reconstruction examination can also be chosen to help clarify the diagnosis.