Low voltage on ECG is seen in some patients who are obese, and sometimes low voltage can occur if the skin is dry when examining the ECG, which is not dangerous. It is also seen in some diseases, such as emphysema, pleural effusion, myocardial infarction, heart failure, pericardial effusion, etc. Serious diseases, such as myocardial infarction, may even have the risk of sudden death. Physical obesity, or dry skin during the ECG examination, interferes with the current conduction of the ECG machine and can manifest itself as a low voltage ECG. There is no danger in this case. Low voltage can occur if emphysema, pleural effusion, and excess gas or fluid in the lungs interfere with electrical conduction. If myocardial infarction, or heart failure or pericardial effusion occurs, weak myocardial contraction and fluid accumulation affect electrical conduction and cause low voltage to occur. It is necessary to go to the hospital in time, check the chest CT, electrocardiogram, cardiac ultrasound, cardiac enzymes, etc. to clarify the condition and actively diagnose and treat. If the ECG test indicates low voltage, it is necessary to consult the doctor in a timely and formal manner to clarify the cause. Some serious diseases, such as myocardial infarction and large amount of pericardial effusion, have the risk of sudden death. Timely and formal medical treatment to avoid delay.