Abstract: Objective To investigate the value of platelet distribution width(PDW) combined with shock index(SI) in predicting prognosis of acute myocardial infarction(AMI). Methods A total of 1 094 patients with acute myocardial infarction admitted to our hospital from March 2011 to March 2013 were followed up for five years. According to the endpoint events, they were divided into good prognosis group(G group, n=894) and poor prognosis group(P group, n=174). The influencing factors of long-term prognosis of patients with acute myocardial infarction were explored by Cox regression. The sensitivity and specificity of SI and PWD and their combination in assessing long-term prognosis were analyzed. Results The mean follow-up time was(47.35±8.57) months. Twentysix(2.38%) patients were lost to follow up. Cox regression showed that both PDW(HR, 1.53; 95% CI, 1.193-1.962) and SI(HR,1.47; 95% CI, 1.089-1.984) were independent predictors for the prognosis of AMI. The sensitivity and specificity of PDW combined with SI in evaluating prognosis of AMI were 75.5% and 100%, and AUC was significantly higher than that of SI and PDW(AUC,0.947 vs 0.863 and 0.765). Conclusion PDW combined with SI has high sensitivity in predicting the prognosis of AMI, which is worthy of clinical application.