Abstract: Objective: To use the morphological characteristics of torn vascular intima to distinguishes true from false lumen of aortic dissection(AD). Methods: Totally 63 MSCTA data of aortic dissection was enrolled into retrospective analysis. On axial images of different segments of the aorta, the intersection angle was measured between torn vascular intima of aortic dissection and both joint point on arterial wall, the angle of true lumen included angle bisector(TLIAB) was calculated, the TLIAB's quadrant was ascertained, the numbers of TLIAB in different segments and different quadrants was statistically compared by using student's χ² test. Results: The maximum number of TLIAB was 126 in different segments of aorta in 63 patients. There were significant differences in the number of TLIAB between different segments(χ²=63.87, P<0.05). There was no significant difference in the number of TLIAB between the same segments and different AD types. TLIAB was most common in the right anterior quadrant, most notably in the descending aortic arch; about 88.89% of the lumen in the right anterior and left anterior quadrant was the true lumen. Conclusion: It is a useful, simple and fast method to distinguish the true lumen from false lumen of aortic dissection according to the morphological characteristics of torn vascular intima.