Objective: To observe the effects of coronary CT angiography (CTA) with low tube voltage, low flow rate and low-dose contrast agent mode on image quality and diagnostic efficiency. Methods: According to random number table method, 70 patients with suspected coronary stenosis who underwent coronary CTA in the hospital were divided into observation group (n=35) and control group (n=35) between December 2022 and December 2024. The parameters setting of coronary CTA in control group and observation group was as follow: (tube voltage: 120KV, flow rate: 3.5-5.0 mL/s, dosage of contrast agent iopamidol: 350mgl/ml; tube voltage: 100kV, flow rate: 3.0-4.0ml/s, dosage of iopamidol:300mgl/ml). The images quality in the two groups was compared. Taking transcatheter coronary angiography (CAG) as the golden standard, diagnostic efficiency of coronary CTA for coronary stenosis in the two groups was observed. Results: There was no significant difference in quality scores of coronary segmentation images between the two groups (P>0.05). Kappa test showed that consistency between CTA and CAG was high in observation group and control group (Kappa=0.799, 0.746). There was no significant difference in sensitivity, specificity or accuracy between observation group and control group (96.55%, 83.33%, 94.29% vs 96.30%, 75.00% 91.43%; P>0.05). Conclusion: Coronary CTA with low tube voltage, low flow rate and low-dose contrast agent mode has no significant effect on images quality, which can ensure image quality and is conducive to the detection of coronary stenosis, with high diagnostic efficiency.