Chronic suppurative otitis media (COST) is a chronic purulent inflammation of the middle ear mucosa, ossicles or deep into the bone, often in combination with chronic mastoiditis. The disease is extremely common. It is clinically characterized by recurrent pus flow in the ear, tympanic membrane perforation and hearing loss. It can cause serious intracranial and extracranial complications that can be life-threatening. Treatment】The treatment principle is to eliminate the cause, control the infection, clear the drainage, completely remove the lesion, prevent and control the complications; rebuild the hearing. 1, etiological treatment: actively treat focal diseases of the upper respiratory tract, such as chronic sinusitis, chronic tonsillitis. 2.Medication. For those with unobstructed drainage, local medication is the mainstay, and in the case of acute inflammation, systemic antibiotics are applied. (1) Local medication: select medication according to different lesions: ① antibiotic aqueous solution or antibiotic and steroid hormone drug mixture, such as 0.3% oclofloxacin ear drops, 0.25% chloramphenicol solution, 3% jasmin solution, etc., for the drum chamber mucous membrane congestion, edema, pus or mucous pus. ②Alcohol or glycerin preparations, such as 4% boric acid alcohol, 4% boric acid glycerin, 2.5-5% chloramphenicol glycerin, etc., are used when the mucosal inflammation gradually subsides, there is very little pus, and the middle ear mucosa is edematous and moist. (2) Precautions for local medication: ①Clean the outer ear canal and the pus in the middle ear cavity before medication, use 3% hydrogen peroxide or physiological saline to clean it, and then swab it with cotton swabs or aspirate the pus with a suction device before dropping the medication. ②Aminoglycoside antibiotics used in the middle ear can cause inner ear poisoning, so they should be used with caution or as little as possible. ③Powder should not be used for small perforations and pus, because it can block the perforation and prevent drainage. Ear drip method: The patient is in a sitting or lying position with the affected ear facing upward. Gently pull the auricle backwards and upwards and put 5-6 drops of the medicine into the external ear canal. Then gently press the ear screen several times with your fingers to encourage the drug to flow into the middle ear through the tympanic membrane perforation. Change position only after a few minutes. Note that the ear drops should be as close to the body temperature as possible to avoid causing vertigo. 3.Surgical treatment. If conservative treatment is ineffective, if CT shows soft tissue shadow in the tympanic cavity or mastoid cavity, if the lesion has invaded bone, and if the patient has cholesteatoma otitis media, mastoid opening + tympanoplasty should be performed to eliminate the diseased tissue, prevent complications, and restore hearing or reconstruct hearing as much as possible.