The electrocardiogram of patients with hyperkalemia will show T-wave hyperacuity, QRS wave widening, PR interval prolongation and P-wave disappearance depending on the value of blood potassium. The normal high blood potassium value is 5.0 mmol/L. When the blood potassium is higher than 5.0 mmol/L, the ECG manifestation of T-wave hyperacuity will appear. When blood potassium is higher than 6.5 mmol/L, it will be accompanied by qrs wave widening. When blood potassium is greater than 7.0 mmol/L, T-wave amplitude decreases, width widens, and PR interval is prolonged. When blood potassium is greater than 8.0 mmol/L, the T wave disappears and sinusoventricular block occurs, while when blood potassium is greater than 10 mmol/L, a wide and distorted sine wave will appear directly. Hyperkalemia is a clinical emergency that needs to be managed, and can be diagnosed by improving electrolyte tests, and should be treated aggressively after diagnosis.