Objective To observe the value of chocolate balloon(controlled dilatation technique)for vascular preparation of endovascular treatments for lower extremity arteriosclerosis obliterans(ASO).Methods Data of 110 patients with lower extremity ASO who underwent vascular preparation with chocolate balloon were retrospectively analyzed.The type of ASO,with calcification or not and so on were recorded,and the success rate of vascular preparation with chocolate balloon and the therapeutic effect of endovascular treatments for ASO were evaluated.Results Among 110 patients,unilateral lower extremity ASO were found in 100 cases,while bilateral lower extremities ASO were noticed in 10 cases,including 100(100/120,83.33%)chronic occlusive lesions,8(8/120,6.67%)stenotic lesions and 12(12/120,10.00%)thrombotic lesions.Calcification with grade 3-4 were observed in 50 lesions(50/120,41.67%).The technical success rate of vascular preparation with chocolate balloon was 92.50%(111/120),while 7(7/120,5.83%)lesions developed flow-limiting dissection after chocolate balloon dilatation and 2(2/120,1.67%)lesions had significant residual stenosis that did not meet the technical success criteria,which underwent stent implantation without drug-coated balloon(DCB).Besides,flow-limiting dissection were noticed in 15 lesions after DCB,hence salvage stents were implanted.The success rate of endovascular treatments of ASO was 100%.Conclusion Chocolate balloon(controlled dilation technique)was valuable for vascular preparation of endovascular treatments for lower extremity ASO.