Objective:To compare and analyze clinical features between patients with early and non‐early acute coro‐nary syndrome (ACS) .Methods :A total of 120 ACS patients were selected ,including 71 patients with early ACS (early ACS group ,onset time≤12h) and 49 patients with non‐early ACS (non‐early ACS group ,onset time >12h) . Risk factors ,clinical features ,mortality ,incidence rates of myocardial infarction ,rehospitalization and major ad‐verse cardiovascular events (MACE) were compared and analyzed between two groups .Results:There were no sig‐nificant difference in percentage of each ACS risk factor between two groups , P>0.05. Compared with non‐early ACS group ,there was significant reduction in incidence rate of heart failure (73.5% vs .54.9% ) ,significant rise in incidence rates of obvious chest pain (32.7% vs .73.2% ) and shock (46.9% vs .62.0% ) in early ACS group (P<0.05 all) ,but there was no significant difference in incidence rate of arrhythmia between two groups (P>0.05) . After one‐year follow‐up , compared with non‐early ACS group , there were significant reduction in mortality (18.4% vs .4.2% ) ,incidence rates of myocardial infarction (18.4% vs .4.2% ) ,rehospitalization (30.6% vs . 14. 1% ) and MACE (38. 8% vs .16. 9% ) in early ACS group , P<0. 05 all .Conclusion:Initial symptom is more ob‐vious ,but related complications are fewer and the prognosis is better in patients with early acute coronary syndrome .