Every contraction and diastole of the heart is accompanied by bioelectric changes, which can be transmitted to the surface of the body, and due to the different distance of each part of the body from the heart, the electrical energy of the ECG signal is also different, but the frequency and strength of the bioelectric changes are regular. If the signal is detected by the instrument, then amplified and recorded, the health of the heart can be derived through analysis. Comparing the normal ECG with the abnormal ECG, the corresponding diagnosis can be made, such as irregular heartbeat rhythm, cardiovascular blockage, early heartbeat, ectopic beats, etc. The ECG can only reflect the abnormalities of the heart from one angle, and the correct judgment can be made only by combining all clinical manifestations.