Objective To construct a risk score for predicting high on-treatment platelet reactivity (HTPR) in patients with acute myocardial infarction after percutaneous coronary intervention, so as to guide individualized antiplatelet therapy. Methods A total of 547 patients with acute myocardial infarction undergoing percutaneous coronary intervention in Fuwai Hospital from Jan. 2013 to Dec. 2013 were enrolled in this study, and their general clinical data and post-operative thrombelastograms (TEG) were collected. The HTPR was defined as ADP-induced platelet-fibrin clot strength (MA_ADP) by TEG (TEG-MA_ADP)>47 mm. Clinical factors available in daily routine were analyzed to screen the related risk factors of HTPR. Clinical factors with a significance level of P<0.05 related to HTPR by multivariate logistic analysis were included in risk score model. The scores of variables were determined based on the odds ratio (OR) values. Results Among 547 patients, 230(42.05%) had HTPR, the TEG-MA_ADP was significantly higher than that of non-HTPR patients ([56.16±6.57] mm vs[26.43±13.88] mm, P<0.001). Univariate and multivariate logistic regression analysis showed that the three following factors were independent risk factors of HTPR:older age (>75 years) was weighted by score 3, female and diabetes mellitus both by score 2 according to OR values, thus a score ranging from 0 to 7 was developed to predict HTPR. The platelet reactivity (TEG-MA_ADP) was (37.79±18.45) mm, (50.04±15.91) mm and (56.50±15.78) mm for score 0-2, 3-5 and 6-7 patients, respectively, and it showed a significant difference among three score ranges (P<0.001). Receiver operating characteristic curve analysis showed that the score>2 was the best cut-off value to predict HTPR (area under the curve was 0.627,95% CI 0.579-0.675,P<0.001). Conclusion Clinical risk score can help to identify patient with high risk of HTPR, so as to guide intensified antiplatelet therapy.