Normal respiration is through the nose, when the nasal cavity space is narrowed due to the disease of the nose itself, causing insufficient ventilation will lead to open-mouth breathing, first of all, we should improve the nasal endoscopy to find the narrow part of the nasal cavity. If the inferior turbinate hypertrophy, you can first choose drug treatment, mainly glucocorticoid nasal spray, can play the role of anti-inflammatory and anti-allergic, adhere to the drug for about 1 month; if the symptoms do not get effective improvement, you can choose surgical treatment, the inferior turbinate of the fracture of the external or part of the mucous membrane excision. If it is caused by deviated nasal septum, surgical treatment is the best plan, because this type is structural rhinitis, caused by bone abnormality, drug treatment has no effect, only improve the space of the nose can solve the problem of open-mouth breathing.