The constant phlegm in the throat may be caused by chronic pharyngitis, reflux pharyngitis, chronic simple rhinitis and other reasons. 1. Chronic pharyngitis: chronic pharyngitis due to chronic inflammatory stimulation, so that the mucous glands under the mucous membrane hypertrophy, hypersecretion, so the patient often has a thick secretion, resulting in phlegm in the throat, may also cause frequent coughing. 2. Reflux pharyngitis: gastric contents reflux to the throat, stimulating mucosal inflammatory edema, glandular secretion increases, resulting in the emergence of phlegm. 3. Chronic simple rhinitis: nasal secretions increase, causing nasal secretions to flow into the throat, forming phlegm and causing phlegm in the throat. It is recommended that patients with phlegm in the throat should go to a regular hospital in time to find out the cause of the disease and take targeted treatment under the guidance of a professional doctor.