Objective:To investigate the clinical value of intravascular ultrasound in diagnosis and therapy in coronary artery disease.Methods:A total of 36 CAD patients were recruited.Coronary artery were examined by CAG and IVUS.Plaque characteristics(soft,fibrous,calcified and mixed plaques)and plaque burden at minimum area were detected and analyzed.The results of before PCI and after PCI derived from IVUS were compared.Results:42 vessels were examined by CAG and IVUS.CAG was not able to identify soft and fibrous plaques and fibrous cap,but could identify calcified plaques,spontaneous dissection,thrombosis and positive vessel remodeling better.IVUS could found ASM and stent inflation flubber promptly.Conclusions:IVUS could accurate determine coronary lesions which CAG could not determine and could give directions to PCI results.