Background In general,percutaneous coronary intervention (PCI) relieves vessel stenosis by implantation of a stent,however,the relationship between plaque characteristics and response after stenting is not clear.Methods We enrolled 68 patients (68 vessels) with diagnosed unstable angina pectoris that prospectively underwent PCI and an optical coherence tomography (OCT) examination was done before and after stenting.Coronary plaques were classified as fibrous,lipid-rich and calcified plaque according to OCT examination,and fibrous cap thickness,lumen eccentricity,stent expansion,stent malapposition,tissue prolapse,thrombosis,dissection and stent symmetry were noted.Results The frequency of prolapse was higher in lipid-rich plaques than fibrous plaques (85％ vs.40％,P ＜0.001).Dissection most often occurred in fibrous plaque compared with lipid-rich and calcified plaques (60％ vs.32％ vs.29％,P＜0.001).The frequency of stent strut malapposition in calcified plaques was higher than firous and lipid-rich plaques (71％ vs.40％ vs.5％,P ＜0.001).In-stent micro-thrombosis was detected only in lipid-rich plaques,with a frequency of 37％ (15/41).The risk factors of micro-thrombosis after PCI were cap thickness (OR 0.903,95％ C/ 0.829-0.985),lumen eccentricity (OR 1.147,95％ CI 1.012-1.30),and stent length (OR 1.495,95％ CI 1.032-2.166).Conclusion Plaque response after PCI is associated with its characteristics,and of those,micro-thrombosis after stenting in lipid-rich plaques was the most significant finding and can be predicted.