The symptoms of facial palsy include loss of frontal wrinkles, enlarged eye fissures, flattened nasolabial folds, drooping corners of the mouth, and skewed corners of the mouth to the key side when the teeth are exposed. When eating, food residues are often retained in the gap between the teeth and cheeks on the sick side, and saliva often flows down from that side. The diagnosis of facial palsy caused by drooping corners of the mouth: 1. Acute anterior spinal cord poliomyelitis, encephalitis, progressive bulbar palsy, congenital facial nucleus formation insufficiency can cause facial nucleus lesion and peripheral facial palsy, to diagnose facial palsy we should go to the neurology department for careful examination. 2. Cerebrovascular disease (hemorrhage, infarction), tumor, inflammation, and multiple sclerosis can cause lesions of the intramedullary root segment of the facial nerve, and peripheral facial palsy can appear, the main point of which is accompanied by adductor nerve palsy on the diseased side, oculomotor disorders, or contralateral hemiparesis. 3. If it is peripheral facial palsy, it cannot be simply called facial neuritis, but also when examined by neurology, and other optical, electrical, chemical, CT and MRI examinations. All these methods of diagnosing facial palsy can be effective in detecting peripheral facial palsy.