EF is the ratio of the heart’s output per beat to the maximum volume of the ventricular end-diastolic volume. In cardiac color Doppler ultrasound, EF is an important indicator of heart failure and the degree of cardiac function. A normal EF value ranges from 50% to 70%, and if it is lower than 50%, it indicates the possibility of heart failure, and depending on the value, cardiac function can be graded. In addition to the EF value, cardiac color Doppler ultrasound can also check the size of the chambers of the patient’s heart as well as the degree of valve regurgitation, insufficient closure or stenosis, cardiac color ultrasound and cardiac color ultrasound in the EF value is the most commonly used laboratory indicators of cardiology.