Objective To investigate clinical application value of spectroscopy CT imaging combined with low concentrations contrast agent in coronary artery CT angiography(CCTA). Methods During the period from January to February 2016 due to the clinical suspicion of coronary artery lesions underwent CCTA examinations of 75 patients, were randomly divided into A group and B group, A group using iodine contrast agent concentration was 300mg/mL, the tube voltage 100kV, B group using iodine contrast agent concentration was 370mg/mL, voltage 120kV, compared two groups left main coronary artery (LM) and proximal left anterior descending (LAD), right coronary artery (RCA) CT value, calculated the signal-to-noise ratio (SNR) and contrast to noise ratio (CNR), image quality evaluation etc. Results Group A, volume CT dose index (CTDIvol), effective radiation dose (ED) and iodine intake respectively (32.08±3.12) mGy, (10.51±2.03) mSv and (13.86±1.09) g, significantly lower than B group (P<0.05). A group image noise (24.12±2.27) HU, significantly higher than group B (P<0.05). A group patients LM, LAD, RCA proximal lumen CT value were (480.15±52.08) HU, (460.15±60.14) HU, (455.13±60.42) HU, significantly higher than group B (P<0.05). Two group LM, LAD, RCA proximal lumen SNR, CNR difference was not statistically significant (P>0.05), two group image quality segment score difference was not statistically significant (P>0.05), good image quality scoring consistency, Kappa value=0.783, P<0.05. Conclusion Spectroscopy CT imaging combined with low concentrations of contrast agent in coronary angiography, can obtain satisfactory image quality, and can significantly reduce radiation dose and iodine intake.