Abstract: Objective To study the mediastinal CT plain scan in diagnosis of ascending aorta calcification before coronary artery bypass. Methods Clinical data about 320 patients (216 males, 104 females) at the age of 38-82 years (mean 61.71 years) who underwent coronary artery bypass in our hospital from December 2011 to November 2012 were retrospectively analyzed.The patients underwent routine mediastinal CT plain scan before operation.The ascending aorta was explored and blocked in patients with ascending aorta calcification and punctured at the place without calcification during operation. Results The mediastinal CT plain scanning showed aorta calcification in 96 patients.The ascending aortic plaques could be touched in 48 patients during operation, especially in those with their age> 60 years.The patients were discharged without complications of the nervous system. Conclusion Routine mediastinal CT scan can show aorta calcif ication in patients with their age> 60 years before operation.Complications of the nervous system should be prevented after operation.