The causes of facial nerve palsy include intracranial diseases, diseases within the temporal bone, cervicofacial diseases, infectious or toxic diseases, etc. Its symptoms include disorder of random movement of facial muscles and lack of clear speech. 1.Causes (1) Intracranial diseases: such as cerebrovascular embolism, traumatic brain injury, multiple sclerosis, encephalitis, cerebral aneurysm, cholesteatoma, fracture of the skull base and so on. (2) Temporal bone diseases: common acute and chronic suppurative otitis media, temporal bone fracture, Bell’s palsy, herpes zoster, jugular vein bulboma, facial nerve tumor, etc. (3) Cervicofacial diseases: violent facial injuries, tumors of parotid gland, surgery, birth injury, deep neck abscess of ear origin, etc. (4) Infectious or toxic diseases: such as diphtheria, lead poisoning, syphilis, etc., which can invade all sections of facial nerve and cause facial paralysis. 2. Clinical manifestations (1) Random movement disorder of facial muscles: when the upper facial muscles have random movement disorder, they cannot furrow the forehead, raise the eyebrows, or close the eyes, and after a long period of time, there is lower lid ectropion, conjunctiva and cornea dryness. In the case of lower facial muscle dyskinesia, the nasolabial folds disappear, and the corners of the mouth are tilted to the opposite side, which is more obvious when the teeth are exposed or when the patient laughs. Inability to puff out the cheeks or whistle. When blowing, the affected cheek bulges out more obviously. (2) Lack of clarity of speech and inability to pronounce explosive sounds such as “wave” and “slope”. (3) When drinking water, it tends to flow out along the corners of the mouth. Food tends to stay between the teeth and cheeks on the same side. When the above symptoms occur, the patient should go to the hospital in time to find out the cause and standardize the treatment under the doctor’s guidance.