A low anion gap is commonly associated with hypoproteinemia, with a focus on improving nutritional status, such as a high-protein diet. Low anion gap is due to a prolonged negative nitrogen balance for various reasons, which reduces plasma proteins in the body and lowers colloid osmotic pressure, resulting in edema. The main cause is due to insufficient protein intake, which is common in hypoproteinemia. Clinical manifestations include edema, malnutrition, emaciation, and weight loss. Treatment is mainly to improve the nutritional status, can be given high protein, high calorie diet to ensure adequate calorie supply. Those with poor digestive function can be given liquid or semi-liquid diet, and supplemented with enough vitamins; if the condition is serious, plasma or albumin can be imported. It is recommended to have a low-salt and low-fat diet. In addition, the primary disease causing insufficient protein intake and excessive loss can be clarified through examination and clinical manifestations. Then actively treating the primary disease can effectively improve the low anion gap. If the above symptoms occur, it is recommended to go to the hospital in time for early and regular treatment.