Objective：To evaluate the image quality and radiation dose of dual-source computed tomography at ultra-low tube voltage （70 kV）. Methods：A total of 90 patients undergoing CT angiography（CTA） of the abdominal aorta and lower extremity arteries were randomly divided into three groups：group A：70 kV，dual-source，and sinogram-affirmed iterative reconstruction（strength level 3）（SAFIRE-3）；group B：100 kV，single-source，and filtered back projection；group C：70 kV，single-source，and SAFIRE-3. Then，the CT values，signal-to-noise ratio（SNR），and contrast-to-noise ratio（CNR） of four vascular regions of interest （ROIs） of the abdominal aorta，the common iliac artery，the femoral artery，and the radial artery were measured，image quality was subjectively scored，and the radiation dose was compared between the three groups. Results：Groups A and C had significantly higher CT values of three ROIs of the abdominal aorta，the common iliac artery，and the femoral artery than group B，and group A had significantly higher SNR and CNR of the three vascular ROIs than groups B and C（P<0.05）. The image quality of the distal small vascular branches was signif－icantly higher in group A than that in groups B and C（P<0.05），but there was no significant difference between group B and group C（P>0.05）. The volume CT dose index volume and dose-length product were significantly different between the three groups（P<0.05），and the values were highest in group B and lowest in group C. The radiation dose in group A was 24% higher than that in group C but 18% lower than that in group B. Conclusion：High-pitch dual-source CTA of the lower extremities at ultra-low tube voltage（70 kV） combined with iterative reconstruction tech－nique can reduce radiation dose，increase the image quality，and contribute to the imaging of distal small vascular branches.