Moderate ST-segment depression is interpreted from an electrocardiogram and indicates an ST-segment downshift of greater than or equal to 0.05mv, which is generally indicative of myocardial ischemia. Moderate ST-segment depression indicates that the degree of ST-segment downshift is greater than or equal to 0.05mv. The most common cause of moderate ST-segment depression is myocardial ischemia, which is often accompanied by T-wave inversion. If the patient has precordial pain and the electrocardiogram shows moderate ST-segment depression, it is recommended to improve the cardiac enzyme profile to further clarify the diagnosis. In addition, moderate ST segment depression can also be seen in cardiomyopathy, hypertrophic cardiomyopathy and so on. ST-segment depression can also be seen in electrolyte disorders, commonly caused by potassium abnormalities in the electrocardiogram ST-T segment changes. ST-segment depression lacks diagnostic specificity. Certain physiological states and non-cardiac diseases can cause ST-segment depression, so abnormal ECG changes should be analyzed based on the clinical presentation. Myocardial ischemia should not be diagnosed on the basis of ECG criteria alone, and when ST-segment depression does not support a cardiac condition, upper abdominal and respiratory conditions should be considered. It is recommended that the patient should go to a regular hospital for timely consultation to identify the cause of the disease and receive targeted treatment under the guidance of the doctor.