Objective To compare the graft patency rates of conventional on-pump coronary artery bypass grafting （CCABG） and off-pump coronary artery bypass grafting （OPCAB） at 2 weeks，3 months and 1 year after surgery. Methods Clinical data of 200 patients who underwent coronary artery bypass grafting （CABG） in the First Affiliated Hospital of Harbin Medical University from May 2010 to November 2011 were retrospectively analyzed. All the 200 patients were divided into two groups according to different surgical procedures they received：CCABG group，61 patients including 32 male patients and 29 female patients with their age of 59.8±4.7 years；and OPCAB group，139 patients including 72 male patients and 67 female patients with their age of 59.6±8.9 years. Graft patency of all the patients was evaluated by 256-slice multislice computed tomography angiography （256-MSCTA） at 2 weeks，3 months and 1 year after CABG and compared between two groups. Results At 2 weeks，3 months and 1 year after CABG，the graft patency rates of left internal mammary artery （LIMA） grafting were not statistically different between CCABG group and OPCAB group，as well as those of great saphenous vein （GSV） grafting （P＞0.05）. The 1 year graft patency rates of LIMA grafting of CCABG group and OPCAB group were 92.31% and 91.94% respectively，and 1 year graft patency rates of GSV grafting of CCABG group and OPCAB group were 91.35% and 90.00% respectively. To compare the graft patency rates of different distal anastomotic locations，grafting to the left anterior descending （LAD） coronary artery had significantly higher patency rate than grafting to the right coronary artery （RCA，P＜0.05）. The 1 year graft patency rates of LAD grafting and RCA grafting were 97.78% and 85.90% respectively. But there was no statistical difference in graft patency rates at different respective distal anastomotic locations between OPCAB group and CCABG group （P＞0.05）. To compare early clinical outcomes of two groups，postoperative mechanical ventilation time，length of ICU stay，24-hour mediastinal drainage，24-hour blood transfusion，length of hospital stay，and hospitalization cost of OPCAB group were significantly shorter or lower than those of CCABG group （P＜0.05）. Conclusion Short-term graft patency rates of CCABG and OPCAB are quite similar. Patency rate of grafting to LAD is higher than that of grafting to RCA. OPCAB can produce better perioperative clinical outcomes than CCABG.