Objective Investigation of the significance for applying the percentage of neutrophils, neutrophil to lymphocyte ratio combined with contrast enhanced ultrasonography in the diagnose of coronary artery disease through examining the percentage of neutrophils, neutrophil to lymphocyte ratio on peripheral blood. Methods 130 patients with acute coronary syndrome (ACS group) , 90 patients with stable angina (SAP group) and 50 nonCAD patients (control group were observed. The neutrophils counts of all the patients were detected and Neut％, NLR were calculated; all the patients were asked to examine enhanced carotid contrast echocardiography. The plaque enhancement (DE) , and luminal enhancement ratio (Ratio) were recorded. The differences in neut％, NLR and CEUS were compared among the three groups. The Pearson correlation analysis was used to analyze the correlation between Ratio and Neut％, NLR. Multivariate logistic regression analysis was used to evaluate the predictive value of Neut％, NLR and CEUS for ACS. Results (1) The value of Neut％, NLR of the peripheral blood, DE, and Ratio in both ACS group and SAP group were higher than those in control group, and the value of ACS group was higher than that in SAP group (P < 0.05 or P < 0.01); (2) The analysis of Linear correlation showed that the ratio of CEUS in ACS patients was positively correlated with Neut％ (r = 0.422, P = 0.001) and NLR (r = 0.407, P = 0.001). (3) The ROC results showed that circulating Neut％, NLR and DE, Ratio play a significant role in the diagnose of unstable plague in CAD patients; (4) Multivariate logistic regression analysis showed that Neut％, NLR, DE, Ratio were independent indicators of the ACS patients (P< 0.05 or P < 0.01).Conclusions Contrast enhanced carotid examination combined with leukocyte analysis on peripheral blood were useful to detect plaque instability and inflammatory response in CAD patients, and it also provide lots of objective evidence for predicting and intervening unstable plaque in CAD patients.