Cerebrospinal fluid leakage belongs to more serious brain diseases, which is mainly diagnosed by clinical symptoms, laboratory glucose oxidase test, CT examination, nasal endoscopy and so on. 1. Clinical symptoms: cerebrospinal fluid leakage is mainly manifested as intermittent or continuous discharge of clear, watery fluid from the nasal cavity, and it is mostly unilateral, and some patients may also be accompanied by decreased sense of smell, hearing impairment, etc. Secondly, it is necessary to pay attention to clarifying whether the patients have traumatic brain injuries and surgical history, which are the common causes leading to cerebrospinal fluid leakage. 2. Glucose oxidase test: it is a traditional diagnostic method, which can infer whether the leaked fluid is cerebrospinal fluid or not by detecting the glucose concentration in the leaked fluid. 3. CT examination: high-resolution CT and three-dimensional CT imaging technology can be used to reconstruct the base of the skull, so as to visualize the fracture of the head and clarify the location of the leak. 4. Nasal endoscopy: it is a routine examination item, when the cerebrospinal fluid continues to flow out, the endoscope can be used to directly find out the occurrence of cerebrospinal fluid leakage, so as to initially understand the phenomenon around the leakage port of cerebrospinal fluid leakage. Therefore, once there is persistent nasal discharge, we should pay attention to it and go to the hospital in time to improve the examination for diagnosis.