Objective To observe the changes of red blood cell distribution width, mean platelet volume and cardiac troponin I in patients with Acute Coronary Syndromes, and to evaluate the value for early diagnosis by using ROC curve. Methods 191 patients with ACS and 206 patients with the chest pain syndromes non-ACS were selected in this study. Electrocardiogram,blood routine,creatinine, LDL-C and cardiac troponin I were determined within six hours after hospitalized,meanwhile the feature of ROC curves was observed. Results There was no significant difference between ACS group and non-ACS group about red blood cell, hemoglobin, platelet,creatinine and LDL-C［(3.82±0.57)×1012/L,(101.3±3.3)g/L,195（98.6-334.8）×109/L,69（45-120）μmol/L,(2.95±0.85)mg/dl vs (3.89±0.50）×1012/L,(103.5±3.7)g/L,201（135.2-346.9）×109/L,71（49-100）μmol/L,(2.82±0.75)mg/dL］ (P＞ 0. 05). Red blood cell distribution width, mean platelet volume and the cardiac troponin I in ACS group［13.70(12.00-15.20)%,9.4（7.42-12.31）fL,(5.63±1.39)μg/L］ were significantly higher than that of non-ACS group［12.60（11.20-13.83）%,8.2（6.24-10.97）fL,(0.04.±0.01)μg/L］ (P＜0.01) .The area under ROC curves of red blood cell distribution width,mean platelet volume and cardiac troponin I were 73.5%, 78.8%, 98.1% respectively, while the best cut-off value was 13.15%, 12.45 fL, 0.06 μg/L respectively. Conclusions The combination using of red blood cell distribution width andmean platelet volume and cardiac troponin I and other conventional cardiac markers might be served as early diagnosis marker for the ACS patients admitted to emergency departments.