Aim To investigate clinical characteristics, outcome analysis and related factors of early left ventricular thrombosis (LVT) in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods With a retrospective study, from January 2019 to December 1,7 patients with acute anterior wall myocardial infarction were enrolled in the Cardiovascular Department of Shenzhen Hospital, Fuwai Hospital, Chinese Academy of Medical Sciences.Among them, 53 patients with early LVT were selected as the STEMI＋LVT group, and 244 patients without LVT were selected as the STEMI group. Collect and compare basic clinical data, occurrence of embolic events, echocardiography and cardiac magnetic resonance imaging data, ventricular morphological characteristics of LVT, coronary angiography, interventional therapy, and medication plans between two groups of patients. Multivariate Logistic regression analysis was used to investigate the related factors of early LVT formation in acute STEMI patients. Results There was no significant difference between the two groups in age, hypertension, diabetes, smoking, multi vessel disease, high sensitivity C-reactive protein (hs-CRP), serum creatinine (SCr), total cholesterol (TC), triglyceride (TG), N-terminal pro-brain natriuretic peptide (NT-proBNP), and the proportion of patients receiving antiplatelet therapy (P＞0.05). The STEMI＋LVT group had a history of previous myocardial infarction, early ventricular aneurysm formation, concomitant shock (SCAI classification), and higher support rates for intra-aortic balloon pump (IABP) or extracorporeal membrane oxygenation (ECMO) compared to the STEMI group (P＜0.05). Left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD) in the STEMI＋LVT group were higher than those in the STEMI group, LVEF in the STEMI＋LVT group was obviously lower than that in the STEMI group (P＜0.05). Multivariate Logistic regression analysis showed that a history of previous myocardial infarction (OR＝3.6,5%CI:1.069～10.592, P＝0.036), early ventricular aneurysm formation (OR＝3.0,5%CI:1.025～8.864, P＝0.047), and concomitant shock (OR＝3.1,5%CI:1.215～9.031, P＝0.017) were associated with an increased risk of early LVT formation in acute STEMI, while LVEF＞40% (OR＝0.3,5%CI:0.054～0.669, P＝0.011) and emergency PCI (OR＝0.4,5%CI:0.089～0.678, P＝0.008) were associated with a reduced risk of early LVT formation in STEMI. Conclusion Early LVT formation in acute STEMI patients is more common in the left ventricular apex, the combination of shock, previous history of myocardial infarction, early ventricular aneurysm, emergency PCI and baseline LVEF＞40% may be independent influencing factors for early LVT formation in acute STEMI patients.