Aim To investigate the predictive value of T wave changes in avL lead in patients with acute coronary syndrome. Methods Electrocardiogram and coronary angiography were performed in 142 patients with acute coronary syndrome, and imaging features were recorded. The prognosis of the patients were followed up. The prognosis group and the prognosis group were classified accorded to the prognosis, and the correlation analysis were performed on the observation items. Results There were 42 patients (poor prognosis group, 29.6%) were reached the end of the cardiovascular event, and 100 patients were good prognosis (good prognosis group, 70.4%). The the avL lead T wave change rates in the good prognosis group were 13.0%, which were significantly lower than 85.7% in the poor prognosis group (P<0.05). The ST segment elevation, ST segment depression, pathological Q wave, etc in the good prognosis group were significantly lower than the poor prognosis group (P<0.05). The rates of coronary artery stenosis in the good prognosis group were significantly higher in the poor prognosis group(P<0.05). COX model analysis showed that coronary stenosis rate, avL lead T wave change, ST segment elevation, and pathological Q wave had independent prognostic value (P<0.05). Conclusion T-wave changes in the avL lead in patients with acute coronary syndrome can predict their prognosis, and the T-wave change in the avL lead is an independent risk factor for the endpoint of cardiovascular events in patients.