Background: Aortic dissection (AD) is a relatively rare but dreadful illness, often accompanied by severe, sharp (or tearing) back pain or anterior chest pain, as well as acute hemodynamic compromise. Painless dissection has also been reported in rare cases and might be misdiagnosed due to its atypical symptoms leading to catastrophic outcomes. Case presentation: The patient was admitted to the hospital due to right limb weakness with speech inability for more than 10 hours. In the routine cardiac ultrasound examination, the avulsion intimal echo was found in the initial segment of the descending aorta. The rupture range was about 11 mm, and the lumen was separated into real and false lumen. Further computed tomography angiography (CTA) examination confirmed the major arterial dissection (De Bakey Type I). Conclusion: We report a case of painless aortic dissection with active carotid artery thrombosis diagnosed by ultrasound and CTA, and to improve the understanding of painless aortic dissection by reviewing relevant domestic and foreign literature.