Under normal circumstances, both nasal passages are clear, and can fulfill the respiratory function smoothly, and keep breathing through the nasal valve area to form laminar flow, turbulent flow, as well as nasal resistance, nasal cycle, etc. to keep breathing and gas exchange normally. Nasal cavity plays a very important role for the body to contact with the external environment, the nasal cavity is divided into left and right each one, the main physiological functions are respiration, resonance, and sense of smell. The nasal valve area is the narrowest part of the nasal airway, also known as the flow-limiting segment, where the inhaled air is divided into laminar flow and turbulent flow after being resisted, and laminar flow constitutes the main part of the gas exchange in the lungs and regulates the temperature and humidity of the nasal cavity. Turbulent flow facilitates the deposition of dust and other particles on mucosal surfaces, and also allows the nasal cavity to regulate airflow. In addition, the nasal cavity also has the presence of nasal resistance, which ensures the process of gas exchange in the alveoli, in addition, the presence of the nasal cycle also allows normal people to unconsciously alternate nasal congestion in order to turn over at bedtime, which can prevent the formation of pressure sores. Under normal circumstances, the nasal cavity can normally complete the respiratory function, completely clear, if one side or both sides of the persistent nasal congestion, it is recommended to consult a doctor in time.