Determining whether patients have volume-responsiveness is one of the frequently asked questions in the intensive care unit, especially in shock patients. Evaluating the volume status and volume responsiveness can help clinical medical staff accurately grasp the patient's cardiac preload, guide reasonable volume management, and help improve patient prognosis. Therefore, many non-invasive and invasive methods have been proposed to evaluate volume responsiveness. Inferior vena cava ultrasound has been widely used to guide the fluid management of critically ill patients due to its simplicity, non-invasiveness, and good repeatability. This article reviews the clinical applications of inferior vena cava ultrasound in fluid management of critically ill patients, so as to provide a reference for circulatory management of critically ill patients.