Postnasal drip clinically known as postnasal drip syndrome, can be diagnosed by nasal examination, nasopharyngoscopy, oropharyngeal examination, imaging examination and other methods of examination. 1. Nasal cavity examination: the mucous membrane can be seen to be swollen, resulting in narrowing of the nasal cavity, and the nasal passage can be seen to be different in nature of secretion or backward drainage to the nasopharynx, or although there is no obvious abnormality in the nasal cavity, the nasopharynx can be seen to be more obvious inflammatory reaction and the presence of mucous secretion. 2. Nasopharyngoscopy: mucosal congestion, mucus adhesion and nasopharyngeal erythema can be seen. 3. Oropharyngeal examination: mucous or mucopurulent secretions can be seen draining downward from the nasopharynx, and the mucous membrane of the area through which the secretions flow is characterized by chronic inflammatory reaction, lymphoid follicular hyperplasia, tonsillar hypertrophy and chronic inflammatory changes. 4. Imaging: chronic sinusitis manifestations, such as nasal turbinate enlargement, sinus mucosal hypertrophy, and even sinus effusion manifestations. It is recommended that the patient timely consultation, under the guidance of the doctor to improve the examination to clarify the diagnosis, targeted treatment.