Objective: To explore clinical characteristics and severity of coronary lesions in young and aged patients with acute myocardial infarction (AMI).Methods: A total of 60 young AMI patients and 60 aged AMI patients hospitalized in our hospital from Oct 2014 to Apr 2016 were randomly selected as youth group and aged group respectively.General data, clinical characteristics, coronary lesion severity and incidence of adverse events during hospitalization were analyzed and compared between two groups.Results: Compared with aged group, there were significant rise in percentages of male (75.0% vs.100.0%), smoking (43.33% vs.76.67%), family history of CHD (18.33% vs.46.67%) and obesity (30.00% vs.53.33%);and significant reductions in percentages of hypertension (63.33% vs.33.33%) and type 2 diabetes mellitus (50.00% vs.13.33%), P<0.05 or <0.01;significant rise in percentages of clear causes (30.0% vs.60.0%), typical chest pain (58.33% vs.86.67%) and STEMI (43.33% vs.76.67%), significant reductions in percentages of old myocardial infarction history (13.33% vs.0), atypical chest pain and NSTEMI, P<0.01 all;significant rise in percentages of single-vessel disease (18.33% vs.63.33%),medium stenosis (16.67% vs.40.00%), and significant reductions in percentages of multi-vessel disease (61.67% vs.20.00%) and severe stenosis (45.00% vs.20.00%) in youth group, P<0.01 all.Compared with aged group, there was significant reduction in incidence rate of major adverse cardiovascular events (88.33% vs.13.33%) in youth group during hospitalization, P=0.001.Conclusion: Compared with aged patients,the symptoms and ECG manifestations are more typical, vascular lesion range is limited, and complications are few in young AMI patients.