Refeeding syndrome (RFS) refers to the clinical syndrome caused by intracellular and extracellular transfer of the body fluids and electrolytes in patients with long-term malnutrition or fasting during the initial stage of active nutritional therapy (enteral, parenteral, or oral). In 2020, the American Society for Parenteral and Enteral Nutrition (ASPEN) defines RFS as a range of metabolic and electrolyte alterations that occur after refeeding. RFS can present as mild RFS only with electrolyte disturbances and few clinical symptoms, or as severe RFS with circulatory and respiratory failure. The clinical manifestations of RFS are diverse and non-specific, which are easy to be ignored by clinicians. The incidence of RFS is 0-80%, which varies with the population and the definition of RFS. The diagnostic criteria for RFS have always been highly heterogeneous, ranging from simple hypophosphatemia to severe low serum electrolyte levels accompanied by fluid imbalance and/or organ dysfunction. The high-risk factors for RFS include patients with anorexia nervosa, patients with mental disorders, and alcohol or drug abusers. The occurrence of RFS in critically ill patients is associated with high mortality rates, ranging from 52.3% to 83.3%.At present, before nutritional treatment, the screening of patients with high risk to develop refeeding problem is mainly based on the National Institute for Health and Care Excellence (NICE) criteria in 2006, but its effectiveness needs to be improved. Therefore, it is necessary to screen and identify high-risk patients early to avoid severe electrolyte disturbance and deterioration of clinical symptoms, thus reduce the risk of death.