Abstract: Objective To compare the effects of high- and normal- dose Clopidogrel on the treatment of acute coronary syndrome after percutaneous transluminal coronary intervention. Methods All 270 participants diagnosed to be acute coronary syndrome from February, 2013 to December, 2015 in our hospital were included and divided into two groups:the high-dose group and the normal-dose group. The high-dose group received Clopidogrel 150 mg/day and the normal-dose group received Clopidogrel 75 mg/day. Comparisons of incidences of stent thrombosis, all-cause mortality and bleeding were made between two groups. Results The incidences had no difference in both groups (P>0.05), and the stent thrombosis incidence and mortality rate had no statistical significance(P>0.05). However, the bleeding events were significantly higher in the high-dose group (P<0.001), which had higher incidence of minor bleeding (P=0.008)and moderate bleeding(P<0.001). Compared with the normal-dose group, the high-dose group treatment did not decrease the risk of stent thrombosis and death (HR=1.32, 95% CI:0.83-1.89, P=0.654) but increased the risk of bleeding events (HR=2.52, 95% CI:1.13-3.03). Conclusion In the treatment of acute coronary syndrome after percutaneous transluminal coronary intervention, patients with high-dose Clopidogrel did not decrease the risk of stent thrombosis and death but had increased risk of bleeding events.