A normal ECG has a heart rate in the range of 60-100 beats, sinus rhythm, PR interval in the range of 0.12 to 0.20 seconds, and so on. ECG includes heart rate, P wave, P-R segment, P-R interval, QRS complex wave, ST segment, T wave and so on. It is a record of the potential difference between the inside and outside of the heart muscle cell membrane, which can reflect the occurrence, propagation and recovery process of cardiac excitation, and is a routine examination for various heart diseases such as myocardial infarction and arrhythmia. Generally, the heart rate of ECG is between 60~100 beats; the P wave time is <0.12 seconds, and the ECG report suggests sinus rhythm; the PR interval time is 0.12~0.20 seconds, the QRS wave is between 0.06~0.10 seconds, the ST segment is not elevated or depressed, and the T wave is not elevated or inverted, etc. It can be said that the ECG is in the normal range. The significance of specific ECG charts is very complex, and the diagnosis of the disease needs to be evaluated in conjunction with other tests and the patient's clinical symptoms, and the final judgment and treatment plan should follow the doctor's diagnosis.