Pus and phlegm in the throat may be related to chronic sinusitis, pharyngitis, pneumonia and so on. It is recommended that the patient go to the hospital in time for a clear diagnosis. 1. Chronic sinusitis: often caused by acute sinusitis, odontogenic infection, trauma and other reasons. It is often characterized by nasal congestion, pus flow, olfactory dysfunction, headache and other symptoms. However, when the pus in the nose flows backward, there will be pus and phlegm in the throat. 2. Pharyngolaryngitis: acute pharyngolaryngitis caused by bacterial infection, mainly manifested as sore throat, burning sensation, thick phlegm and so on. 3. Pneumonia: Inflammation of the lungs due to infection, mainly manifested as fever, chills, coughing, coughing up sputum, can also be accompanied by chest pain, dyspnea and other symptoms. It is recommended that the patient go to the hospital in time to complete the relevant examinations and standardize the diagnosis and treatment.