【Objective】To investigate the clinical value of using prospective ECG-gating Helical protocol in whole aorta and coronary arteries CT angiography combined with low tube voltage，low contrast medium injection rate and dose technology.【Methods】 A total of 60 patients（heart rate≤ 75 bpm and normal heart rhythm）with suspected aortic disease or post-operation were randomly divided into 2 groups：G1（n = 30；tube voltage：80 kV；contrast medium injection rate：3 mL/s；contrast medium dose：0.65 mL/kg） and G2（n = 30；tube voltage：120 kV；contrast medium injection rate：4 mL/s；contrast medium dose：1.2 mL/kg）. The two groups underwent aorta angiography with prospective ECG-gating Helical protocol by using 320-detector CT. The mean CT values and standard deviation of aorta，coronaries and adjacent adipose tissue were measured，signal to noise ratio（signal-to-noise ratio，SNR）and contrast to noise ratio（contrast-to-noise ratio，CNR）were calculated. The subjective quality scoring of 3-d post-processing images were evaluated independently by 2 senior radiologists. The mean CT values and standard deviation of aorta，coronaries and adipose tissue，SNR，CNR，subjective quality scoring，contrast medium dose and radiation dose were compared and analyzed. 【Results】The abnormal and normal rate of aorta in two groups were 83.33%（25/30），16.67%（5/30）and 86.67%（26/30），13.33% （4/30）；while the abnormal and normal rate of coronary arteries in two groups were 43.33%（13/30），56.67%（17/30）and 53.33% （16/30），46.67%（14/30）. SNR values of ascending aorta，descending aorta，abdominal aorta，superior mesenteric artery，bilateral renal artery，left main coronary artery，left anterior descending branch ，left circumflex branch，right coronary artery and CNR values of abdominal aorta，superior mesenteric artery，bilateral renal artery，left anterior descending branch，left circumflex branch had no statistical significance，while the other indicators were significant differences between the two groups. The radiation dose and the contrast medium dose of G1 was significantly lower than G2（P < 0.05）. There was no difference in the subjective image quality of 3D post-processing images between the two groups（P > 0.05）.【Conclusions】Using prospective ECG-gating Helical protocol in whole aorta and coronary arteries CT angiography combined with low tube voltage，low contrast medium injection rate and low contrast medium dose technology can help to reduce radiation and contrast medium dose without impacting on the imaging quality satisfactorily.