The basic prerequisite for ventilator withdrawal is that the primary disease requiring ventilator support has been thoroughly treated or effectively controlled. The second prerequisite is that the patient’s spontaneous breathing can be restored and the patient has the ability to expel sputum on his own. In addition, the patient’s hemodynamic stability, respiratory function stability and internal environment stability are all indications for ventilator withdrawal. Hemodynamic stability includes blood pressure index and heart rate index. Respiratory function stability includes pH, partial pressure of oxygen and oxygenation index. Internal environmental stability includes electrolyte stability and acid-base balance in the patient.