To explore the significance of circulating miRNA-1 (miR-1) released within 3 h after the onset of acute chest pain in the diagnosis and prognosis of acute myocardial infarction (AMI).A total of 337 patients with acute chest pain within 3 h were enrolled in this study and divided into AMI group and non-AMI group. The AMI diagnostic efficacy of miR-1 was determined and compared with that of cardiac troponin I (cTnI). The patients were followed up for 720 d after treatment. The significance of circulating miR-1 in AMI prognosis was assessed using univariate and COX regression analysis.There were 174 patients in AMI group, 163 in non-AMI group. Circulating miR-1 level was significantly higher in AMI group than in non-AMI group (P < 0.001). The AMI diagnostic efficacy of miR-1 and cTnI were similar (P > 0.05). We established two AMI diagnostic models, the AUC values of which were larger than that of cTnI or miR-1 (P < 0.05). When miR-1 combined with CK-MB, cTnI, and other clinical and laboratory parameters (model 2), the AUC was the largest (AUC: 0.961) and had the highest diagnostic efficiency. Circulating miR-1, Killip classification, and treatment method were influencing factors for AMI prognosis (P < 0.05).Circulating miR-1 within 3 h of acute chest pain has the potential diagnostic value for AMI, and which is an independent risk factor for the prognosis of AMI and can be used to predict AMI prognosis.