The invention relates to a mussel adhesive protein (MAP) and an application thereof in inhibiting catarrh, and specifically, to applications of a MAP or a product thereof in oral mucositis, rhinitis, otitis media, pharyngitis, laryngitis, bronchitis, esophagitis, gastritis, enteritis, cervicitis, endomyometritis, inflammation resulting from inhalation injury, and oral cavity cancer, nasopharyngeal cancer, carcinoma of middle ear, conjunctival cancer, laryngeal cancer, lung cancer, esophageal cancer, stomach cancer, bowel cancer, cervical cancer, endometrial cancer, and other cancers resulting from the inflammation. The MAP can inhibit symptoms such as flush, fever, swell, and pain owing to catarrh, facilitating healing, relieving itch and pain, and having broad applications in the fields of medicines, cosmetics, medical products, disinfection products, healthcare products, foods, and household goods.