Acute myocardial infarction (AMI) is a serious cardiovascular disease caused by acute or persistent ischemic and anoxia of the coronary artery. A more practical and effective risk model is still remained to be established for AMI patients. This study aims to investigate the predictive value of prothrombin time (PT) in AMI patients. In this study, 2734 AMI patients available in the public MIMIC III clinical database were investigated, with 629 deaths occurring within 2-year follow-up. More than 20 risk factors including demographics, clinical disease history, laboratory test information, surgery history, and mediation information were analyzed as potential predictors for all-cause mortality in AMI patients. After adjustment for other covariates, PT was showed to be a significant risk factor for all-cause mortality in AMI patients (adjusted hazard ratio, 4.04; 95% confidence interval, 2.83 to 5.75) from Cox regression analysis. We also developed a comprehensive risk model for AMI mortality using multivariate Cox proportional hazards model based on the above 20 risk factors. Combined with PT, the model achieved a good accuracy with an AUC (area under ROC curve) of 0.843. Overall, PT is an independent predictor for 2-year mortality in AMI, and it might be useful in identifying AMI patients with a high risk for mortality.