Aim To qualitatively and quantitatively evaluate the influence of plaque calcification on the diagnostic accuracy of dual source CT (DSCT) coronary angiography for coronary stenosis assessment. Methods The retrospective analysis enrolled 224 patients. They were diagnosed as coronary artery disease by DSCT angiography, and then received selective coronary angiography. There were 375 lesions with significant coronary stenosis in 224 patients according to DSCT. Of 375 lesions, 234 lesions were with calcification. The influence of characteristics of lesions on accuracy of DSCT angiography for coronary stenosis assessment was evaluated. These characteristics included calcification degree of lesions, artery external diameter of calcified lesions, length of calcified lesions and location of calcified lesions. Results For mild to moderate calcified plaque and severe calcified plaque, DSCT overestimated coronary stenosis by 6.8% (P＝0.0028) and 18.8% (P＜0.0001) separately, and the overestimation of stenosis was more obvious in severe calcified lesions (P＝0.002). For calcified lesions with artery external diameter＜3 mm and artery external diameter≥3 mm, DSCT overestimated coronary stenosis by 7.2% (P＝0.0026) and 17.1% (P＜0.0001) separately, and the overestimation of stenosis was more obvious in calcified lesions with artery external diameter≥3 mm (P＝0.001). There was no difference in the diagnostic accuracy of DSCT for calcified plaques with different lengths (P＝0.792). Conclusion The lesion calcification makes DSCT angiography overestimate coronary stenosis. This phenomenon is more likely to occur in the severe calcified lesions and calcified lesions with artery external diameter≥3 mm.