Currently, tympanocentesis and tympanotomy tubes are still the main treatment methods for cSoM, but they cause varying degrees of damage to the tympanic membrane, and tympanotomy tube drainage can lead to tympanosclerosis, calcium spots, and even permanent tympanic membrane perforation, resulting in hearing loss. Tympanic membrane puncture and tympanotomy placement can only drain the tympanic chamber and reduce the negative pressure in the middle ear, but if the eustachian tube is not open, the middle ear can form negative pressure again after removing the ventilation tube, resulting in the recurrence of fluid. The epidural catheter is smooth at the tip and easy to insert. The depth of insertion is estimated according to the scale on the catheter, and a mixture of dexamethasone and chymotrypsin is injected once a week. Dexamethasone can also reduce the mucosal epithelium of the eustachian tube and local metaplasia. The greatest advantage of this method is that it is non-invasive, simple to operate, less painful for the patient, low cost, and can be administered continuously through an indwelling catheter.