Objective To investigate the difference in coronary CT angiography (CTA) imaging value under 128 slice dual source CT 3 scan mode. Methods 123 patients who underwent CTA examination were taken as the research objects. According to the random number table method, the patients were divided into A, B, C of three groups with 41 cases in each group. Group A was canned with a retrospectively ECG-gating low pitch spiral (LS) mode. Group B was scanned with a prospective ECG triggering sequence (S) mode and group C was scanned with a high pitch spiral (FS) mode. The image quality, scanning time, radiation dose length product (DLP) and effective dose (ED) under different modes were compared among the three groups. Results ①According to 15 segment division method, the enrolled 123 patients were evaluated with 1736 coronary artery segments. The differences in subjective score and good and excellent rate of image quality among the three groups were not statistically significant (P>0.05); ②Among the three groups, the scanning time, DLP and ED of group A were significantly higher than those of the other two groups, followed by group B and group C was the lowest. The differences between groups were statistically significant (P<0.05). Conclusion The LS,S and FS of three kinds of scanning modes of 128 slice dual source CT are of ideal imaging value and the image quality is good; The radiation dose of FS mode is lower than that of S and LS mode. It can be used as an effective means of low radiation dose coronary CTA in the clinical diagnosis and treatment to improve the prognosis level of patients.