Background: Ascending aortic aneurysm is a common clinical disease, whereas the aneurysm at the incision of ascending aorta after valve replacement has not been reported. Aims: We report a case of giant ascending aortic incision aneurysm requiring surgical correction after double valve replacement. Materials & Methods: A 45‐year‐old male was referred to our department with dyspneic respiration after exercises for 1+ months, having previously undergone a mitral and aortic valve bivalve replacement 15+ years ago. The parasternal long-axis section of transthoracic echocardiography provided that the diameter of ascending aorta was thickened( 59mm). Computed tomography angiography (CTA) of the aorta showed a localized anterior protrusion aneurysmal of the ascending aorta with a diameter of approximately 69 mm, and the tube wall was severely calcified. Results: Under cardiopulmonary bypass, the large aneurysm was incised and the artificial blood vessels were replaced. The patient achieved an uneventful postoperative recovery with no significant complications. Discussion: Ascending aortic incision aneurysm has the same treatment regimen as ascending aortic aneurysm although it’s extremely rare. Conclusion: Open surgery was indispensable in this case owing to the large aneurysm and the condition liable to rupture.