Objective To investigate the correlation between circulating uncoupling protein 2(UCP2) level and severity of coronary artery disease(including Gensini score and criminal vessel counts)in patients with stable coronary artery disease(SCAD),and to analyze the predictive value of circulating UCP2 and urine acid (UA)for SCAD. Methods Three hundred and thirty patients from June 2015 to June 2017 were enrolled. Two hundred and forty patients with SCAD(SCAD group),90 patients without coronary artery disease(control group) were diagnosed. The circulating UCP2 level was detected by enzyme linked immunosorbent assay (ELISA) sandwich method. Results The levels of circulating UCP2 and UA in SCAD group were higher than those in the control group(UCP2[1.60(0.67,4.60)ng/mL]vs.[0.42(0.28,0.59)ng/mL](P<0.01),UA[(365.74 ± 66.06) μmol/L] vs. [(268.11 ± 45.81)μmol/L],P < 0.01). Multivariate logistic regression analysis showed that UCP2 (OR = 1.010 ,95% CI :1.001 ~ 1.020 ,P = 0.025)and UA(OR = 1.039 ,95% CI :1.007 ~ 1.072 ,P < 0.05)were independently associated with SCAD. Correlation analysis showed that the circulating UCP2 level was positively correlated with Gensini score(r=0.780,P<0.01)and criminal vessel counts(r=0.543,P<0.01). The receiver operating characteristic curve(ROC)showed that the optimal cutoff point of the circulating UCP2 level predicting SCAD was 0.64 ng/mL,and the sensitivity was 0.833 and the specificity was 0.944. No significant difference was observed in area under the curve between circulating UCP2 and UA(ΔAUC). Conclusion The high circulating UCP2 level indicates more severe coronary lesions in patients with SCAD. Circulating UCP2 level may be a new indicator of predicting SCAD,equal to the traditional oxidative stress related indicator of serum UA.