Aim To retrospectively assess the effectiveness and safety of China-made drug eluting stent （CM-DES） implantation for the treatment of mild-to-modest calcified lesions in patients with acute coronary syndrome （ACS）.Methods Three hundred and twenty consecutive patients of ACS with 434 ischemia related lesions were implanted with CM-DES and received 6～12 months angiographic follow-up. The patients were divided into two groups according to whether the calcification exists or not: non-calcification groups （n267） and calcification group （n167）. Lesions treated with CM-DES were subjected to quantitative coronary angiography （QCA） at immediately and 6～12 months following stenting. Results Baseline clinical, demographic or angiographic characteristics were well comparable between the two groups. At follow-up, no differences were found between the two groups regarding in-stent restenosis （ISR） and in-segment restenosis rate （ISRR） （ISR: 3.9% vs. 4.3% P0.079 ISRR: 8.9% vs. 10.7%, P0.449）. The similar result was also observed concerning the target lesion revascularization （5.1% vs. 6.7% P0.401）. Besides, no difference about in-stent late loss （ISLL） and overall thrombosis rate （TR） was detected in both groups （ISLL: 0.18±0.42 mm vs. 0.19±0.43 mm TR: 1.7% vs. 1.4%, P>0.05 respectively）. Conclusion Our results indicated that implantation of CM-DES for patient of ACS with mild-to-modest calcified lesions was effective and conferred to similar outcomes compared with non-calcified coronary arteries without additional increase in major adverse cardiac events.