Oxygen machine oxygen time can not be generalized, different causes and different lung function have different oxygen time, it is recommended that under the guidance of the doctor according to their own conditions for oxygen. Oxygen concentrator is a kind of device that can satisfy patients’ oxygen intake at home, mostly used by patients with hypoxia symptoms. 1. Causes: There are many causes of hypoxia, such as pneumonia, chronic obstructive pulmonary disease (COPD) and heart failure. For patients with chronic obstructive pulmonary disease combined with respiratory failure, it is recommended to use nasal cannula for oxygen intake, with an oxygen flow rate of 1~2L/min, and an oxygen intake time of 10~15h/d, mostly with low-flow oxygen intake (oxygen concentration of 28%~30%). While patients with pneumonia and heart failure mostly decide the oxygen intake time according to the symptoms, if the primary disease is controlled, the oxygen intake time can be gradually reduced. 2. Lung function: patients with fair lung function may not need oxygen. However, if the lung function is poor, it is necessary to prolong the time of oxygen intake, and if necessary, it can be continued for 24h oxygen intake. Therefore, the oxygen inhalation time of the oxygen machine is decided according to the different causes and lung functions, and it is recommended to carry out the correct oxygen therapy under the guidance of the doctor.