Objective To investigate the clinical diagnostic value of electrocardiogram(ECG)in patients with low blood potassium.Methods From January 2015 to October 2015,patients with low blood potassium were given ECG examination in Yueqing Maternal And Child Health Care Hospital.The relationship between low blood potassium and ECG changes was analyzed.Results The concentration of serum potassium in patients with 0.9 -2.5mmol/L electrocardiogram U wave change,T wave change,ST segment changes,Q -T prolongation,arrhythmia were significantly higher than that of serum potassium concentration in 2.6 -3.4mmol/L patients,and the difference was statistically significant (χ2 =4.63,4.10,4.47,5.01,4.92,all P <0.05).Of patients with hypokalemic ECG showed characteristics of U wave amplitude increased,ST segment depression,T wave amplitude decreased,QT interval prolongation,arrhythmia,of which the most common was premature ventricular contractions,severe low blood potassium could also be occurrence of malignant ventricular arrhythmia.Conclusion Low blood potassium has characteristic changes of ECG,ECG as a noninvasive,simple and quick examination,which is helpful for the rapid diagnosis of low blood potassium.