The main cause of phlegm and yellow nasal discharge is the clinical postnasal drip syndrome, which is most common due to chronic or acute rhinitis or sinusitis. Because of chronic rhinitis and sinusitis in the clinic, when there is nasal congestion, yellow pus nasal discharge and poor ventilation of the nose, the nasal secretions will backflow into the pharyngeal cavity and flow into the pharyngeal cavity after following the nasopharynx. After the secretion hangs in the pharyngeal cavity, it stimulates the inflammatory reaction of the mucous membrane of the pharyngeal cavity, and the foreign body sensation is more obvious. Many patients feel that there is more phlegm in the pharynx, and the itching symptoms are more obvious, and they seek treatment for pharyngitis in the ENT clinic. In fact, the treatment of this disease should first eradicate rhinitis in order to finally relieve the symptoms of pharyngeal cavity.