Objective To explore the application value of the single cycle reconstruction algorithm in improving image quality of free-breathing 256-slice row coronary computed tomography angiography (CCTA) with retrospectively electrocardiogramgated spiral acquisition mode. Methods Twenty-four patients whose CCTA images had motion artifact were recruited in this study between Jun.10 and Jul. 10, 2017. CCTA was examined with the retrospectively electrocardiogram-gated spiral scanning mode. All images were reconstructed using single cycle reconstruction (single cycle group) and multi-cycle reconstruction (multi-cycle group) methods. The two reconstruction algorithms used same phase for analyzing data. The mean CT value, image noise, signalto-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared between the two groups. T test was performed to analyze the objective indicators, and χ² test was performed to analyze the subjective indicators. Results Totally 350 segments of coronary were evaluated in this study. Diagnosis rate of coronary segment image quality with single cycle reconstruction was 98.3% (344/350), which was significantly higher versus 84.0% (294/350) with multi-cycle reconstruction (χ²=44.241, P<0.05). The image noise was significantly higher in the single cycle group than that in the multi-cycle group ([51.3±9.8] HU vs[40.7±6.0] HU, t=-4.647, P<0.05). There was no significant difference in SNR between the two reconstruction algorithms (t=0.941, P=0.351). The CNRs were not significantly different in the ascending aortic root, left main coronary or proximal, middle, and distal right coronary between the two reconstructive algorithms (t=1.039, 0.610, 0.571, 0.438, and 0.396; P=0.304, 0.548, 0.574, 0.666, and 0.696). Conclusion Single cycle reconstruction technique can reduce motion artifact caused by unanticipated free-breathing or heart fluctuations in CCTA under the retrospectively electrocardiogram-gated spiral scanning mode and increase diagnosis confidence of doctors.