In order to prevent any missed diagnosis, the common ECG interpretation is as follows: firstly, the heart rate should be judged roughly according to the waveform interval; then look for P waves, which can reflect the enlargement of the left and right atria, but there may be no P waves, such as sinus arrest, atrial flutter, atrial fibrillation, etc. The starting point of P waves to the starting point of QRS wave group is the PR interval, and the prolonged PR interval is seen in different degrees of atrioventricular block, and the shortened PR interval is seen in short P-R syndrome and pre-excitation syndrome. The subsequent waveform is the QRS wave group, which responds to the depolarization of the ventricles and can reflect right and left ventricular hypertrophy and various bundle branch conduction blocks. If pathological Q waves are found, it indicates old myocardial infarction in the corresponding leads; if ST-segment elevation or depression is found, it indicates myocardial injury; if T-wave hypoplasia, inversion, hyperacusis, and bidirectionality are found, it indicates myocardial ischemia. Under normal setting, the horizontal line of ECG paper indicates the time, one frame represents 0.04s, and the vertical line indicates the voltage, one frame represents 0.1mv. Proper understanding of these reference standards will help the interpretation of ECG.