Objective To investigate the influence from the left pulmonary artery (LPA) with different stenosises (50%,20%,0%) after complete repair of tetralogy of fallot (TOF) on the hemodynamic features using computational fluid dynamics(CFD). Method The 3D models were reconstructed by the computer tomography (CT) images. CFD simulations were performed on these three models to describe the flow characteristics of the main pulmonary artery and the bifurcations such as average speed in LPA and right pulmonary artery(RPA), flow patterns, static pressure and wall shear stress. Results In the unsteady state simulation, different regurgitation and flow velocity distribution can be easily found in the start of LPA due to the stenosis rate of LPA, while the flow velocity distribution is uniform in the RPA. The flow velocity distribution, static pressure, pressure drop and wall shear stress are also different in these three models. Conclusions It is important to expand the branch pulmonary arteries during the TOF operation. LPA stenosis may be an early and important cause of pulmonary artery regurgitation. The use of CFD simulation can provide the early reference information for the effect after TOF operation.