Objective To identify clinical significance of high level cardiac troponin I （cTnI） in the early postoperative period of off-pump coronary artery bypass grafting （OPCAB） and its predictive value for early clinical outcomes. Methods A total of 240 patients undergoing isolated OPCAB in the Department of Cardiac Surgery of People’s Hospitalof Peking University during 2011 were recruited in the study. There were 164 males and 76 females with their age of 36-83（62.07±8.24） years. Serum cTnI levels in 4-6 hours and 12-18 hours after OPCAB were monitored. Influential factors and its predictive value for early clinical outcomes of OPCAB were analyzed. Binary logistic regression analysis，correlation analysis and receiver operating characteristic （ROC） curve were performed for statistic analysis. Results Serum cTnI level in 4-6 hours after OPCAB （TNI0） was 1.28±0.40 ng/ml，and serum cTnI level in 12-18 hours after OPCAB （TNI1） was 3.60±0.74 ng/ml. Binary logistic regression analysis revealed that graft number was significant influential factors of TNI0 （P=0.000） and TNI1 （P=0.010）. Serum cTnI level in 12-18 hours after OPCAB was significantly correlated with early clinicaloutcomes of OPCAB （P＜0.05），but the correlational relationship was not b （correlation coefficient＜0.5）. ROC curveanalysis showed that serum cTnI level in 12-18 h after OPCAB had higher predictive value for patient prognosis （P＜0.05）. Serum cTnI level higher than 1.49 ng/ml in 12-18 h after OPCAB had good predictive value for postoperative ECG changes，use of intra-aortic balloon pump （IABP） and in-hospital mortality. Conclusions Serum cTnI level increases in varying degrees in the early postoperative period of OPCAB. Together with ECG changes，serum cTnI level can be used for early diagnosis of perioperative myocardial infarction with significant predictive value for early clinical outcomes of OPCAB.