Objective To investigate the application of 256-row detector CT for coronary CT angiography in single cardiac cycle in patients with high heart rate. Methods In this study, 134 cases of suspected coronary artery diseasewith a heart rate of ≥80 beats/min treated in the cardiovascular department of our hospital from January 2014 to December 2017 were selected and divided into three groups according to the real-time heart rate showed by the scan, namely group A (80-89 beats/min, n=82), group B (90-99 beats / min, n=29) and group C (≥100 beats /min, n=23). Then the image quality grade and score of standard (STD) reconstruction and snap shoot freeze (SSF), CT volume dose index (CTDIvol), dose length product (DLP) and effective dose (ED) were compared between groups. Results The proportions of excellent, good, middle and poor imaging quality had no difference among three groups (P>0.05). The proportion of good was highest in group C, and the proportion of poor was highest in group A, with no statistic difference (P>0.05). The diagnosable segmental arteries of SSF were more than that of the STD (P<0.05). The diagnosable branches and segments of SSF were also more than those of the STD (P<0.05). No difference was found in the CTDlvol, DLP and ED between the 3 groups (P>0.05). Conclusion The feasibility of 256-row detector CTor coronary CT angiography in single cardiac cycle in patients with high heart rate is relatively high, which is characterized by the low radiation dosage, and the image quality can be improved with the assistance of SSF.