There is no fixed value for the size of the human left lung, but the overall average is around 30 centimeters, the size of the lung is slightly smaller than the size of the thorax, because the left lung covers the heart, so the left lung is smaller than the right lung, the size of the left lung is related to the individual’s physical fitness, gender, body type, height, weight and long-term exercise will affect the size of the lung. Higher height, body type fat and long-term sports people, the size of the left lung will be relatively larger than people of the same age, the general male left lung is larger than the female left lung, if there is no deformity of the chest, such as chicken chest, funnel chest, etc., the lungs do not have emphysema, airway dilatation, chest radiographs, chest CT and other imaging tests can determine the relative size of the left lung, the size of the left lung at this time is the size of their own relative to the normal size. The lung is an important place for gas exchange in the human body, when there is dyspnea, cyanosis and chest pain, it is recommended to go to the regular hospital in time to relieve the cause of the disease as soon as possible, and restore health, do not be negligent, so as not to delay the condition.