Wellens syndrome, also known as left anterior descending T wave syndrome, is characterized by symmetric deep inversion of the T wave, no ST-segment shift or mild elevation, no pathologic Q wave, and poor R-wave progression in the chest leads. 1. The T wave is symmetrical deep inversion: mainly in V2 and V3 leads, and a few can be extended to V1 and V4-V6 leads; the other T wave is positive-negative biphasic, mainly in V2 and V3 leads. 2. No ST segment shift or mild elevation (<0.1mV): most patients do not have mild ST segment elevation in the chest leads, and a few patients have mild ST segment elevation, which rapidly decreases to the isoelectric line. 3. No pathologic Q wave and poor R wave progression in the chest lead: there is no pathologic Q wave in the chest lead, and the QRS wave in the chest lead shows poor R wave progression, and finally QS type. Wellens syndrome is a relatively rare and easily overlooked characteristic electrocardiographic phenomenon in acute coronary syndromes. The mechanism of its occurrence is not fully understood, and it may be related to myocardial ischemia caused by coronary stenosis, and cardiomyocyte tonicity and ischemia-reperfusion. Associated risk factors include diabetes mellitus, dyslipidemia, obesity, hypertension and smoking. When ECG abnormalities are detected, it is recommended to seek prompt medical attention to improve the examination and timely treatment.