Objective：To characterize the anatomic morphology of pulmonary vein ostium by 2-D and 3-D computed tomography angiography.Methods: Thirty patients with paroxysmal/persistent atrial fibrillation (AF) undergoing computed tomography angiography before catheter ablation of AF were analyzed for the anatomic morphology of pulmonary vein ostium in 2-D and 3-D manner.Results: The diameter in axial,coronal and sagittal views of diameters of the pulmonary veins ostium (PVs) were (16.90±4.79) mm,(21.37±4.23) mm,(22.41±3.96) mm in the left superior pulmonary vein(LSPV),(13.50±3.99) mm,(15.84±3.22) mm,(16.82±3.63) mm in the left inferior pulmonary vein(LIPV),(17.77±4.69) mm,(19.11±4.10) mm,(19.71±4.33) mm in the right superior pulmonary vein(RSPV),and (15.33±3.88) mm,(16.20±4.00) mm,(17.10±4.24) mm in the right inferior pulmonary vein(RIPV).The maximal and minimal diameters (dmax and dmin) of PVs in 3-D view were (24.30±4.54) mm,(17.76±4.24) mm in LSPV,(19.10±4.45) mm,(12.27±3.52) mm in LIPV,(22.99±5.04) mm,(16.19±4.87) mm in RSPV,and (18.63±4.60) mm,(14.46±3.48) mm in RIPV.There is difference of diameters between SPVs and IPVs （P<0.01）in two-dimensional and three-dimensional view except for RIPV. Conclusion: CT imaging can present precise 3-D reconstruction of the pulmonary vein ostium,allowing for understanding the details before catheter ablation.There is great variance in the dimension of the pulmonary vein ostium among individuals,which should be taken into consideration before operation.