Potassium supplementation in the course of treatment of patients with heart failure is needed because the application of diuretics can lead to the occurrence of low potassium. Patients with heart failure must apply diuretics to excrete sodium and drain water, which reduces the burden on the heart, especially in severe cases of heart failure when the amount of diuretics is very large, and only after the condition is stabilized can it be changed to a maintenance amount of diuretics, especially tabular diuretics, such as furosemide. They are applied in large doses so that water and sodium are excreted through diuretics, reducing the burden on the heart, which can relieve pulmonary stasis and reduce edema. After the diuretic application of large doses of increased urination, the blood potassium concentration will fall, if the blood potassium is low will lead to some cardiac arrhythmia, especially serious arrhythmia, which may aggravate the condition will lead to sudden death may, so diuretics should be accompanied by supplementation of potassium, but also to monitor the ionic situation, adjust the dose of potassium.