Simple sodium supplementation for hyponatremia in the elderly is a high-salt diet; taking salt capsules, and intravenous sodium supplementation in severe cases. The normal value of blood sodium is 135～145 mmol/L. Hyponatremia in the elderly is defined as age greater than 60 years old and blood sodium lower than 135 mmol/L. Hyponatremia is a decrease in the concentration of sodium in plasma, and the total amount of sodium can be decreased, normal or increased. The main symptoms are weakness, nausea and vomiting, headache and drowsiness, painful muscle cramps, neuropsychiatric symptoms and reversible ataxia. In case of mild hyponatremia with no uncomfortable signs or symptoms, one can go for a review of the blood sodium concentration after a period of time until the normal concentration is restored through a high salt diet, eating more salty food, taking salt capsules, and so on. If severe hyponatremia, and uncomfortable symptoms, should consult the doctor in time, can through the intravenous supplementation of sodium chloride injection, timely identification of the causes of low sodium, the cause of treatment, so as not to delay the condition.