The formula for calculating sodium supplementation for hyponatremia is Supplemental Sodium (mmol) = (Normal Blood Sodium – Measured Blood Sodium) x Body Weight (Kg) x 0.6. The unit of blood sodium in the above formula is mmol, if the calculation is how many grams of sodium is needed, then the calculated value needs to be divided by 17. It should be noted that if it is a boy, the last is multiplied by 0.6, and if it is a girl, then it is multiplied by 0.5. The rehydration of the same day is only half of the calculated amount of rehydration, and the rate of infusion of 3% hypertonic saline is less than 100~150 ml/L. If there is severe sodium deficiency and shock, the rehydration rate should be less than 100~150 ml/L. If shock occurs with severe sodium deficiency, blood volume should be replenished first to improve microcirculation and tissue and organ perfusion. The amount of sodium supplementation for hyponatremia should be timely adjusted according to the actual situation under the calculation of professional doctors, in order to prevent the counterproductive cause of hypernatremia or serious consequences.