Aiming at the problem that the nozzle outlet streamline is relatively divergent,which was found in the flow direction test of an aeroengine bearing oil supply nozzle,a three-dimensional computational fluid dynamic model of nozzle was established by using the realizable k-ε turbulence model of the three-dimensional fluid simulation software.The three-dimensional flow field in the nozzle was simulated and analyzed,and the flow rate and the streamline cylindricity outside the nozzle orifice were investigated.Based on the simulation results of the three-dimensional flow field,several different optimization schemes were put forward,and the performance of the fuel supply nozzle was investigated respectively.The results show that the internal flow field of the nozzle outlet pipe section directly determines the cylindricity and the divergence of the external streamline of the nozzle.Reasonably arranging the upstream structure and appropriately increasing the length diameter ratio of the outlet pipe section can effectively suppress the swirl in the main flow area and reduce the divergence of the external streamline of the injection hole.The new embedded plug installed on the outlet pipeline side can suppress the swirl in the orifice area and make the cylindricity of the streamline outside the nozzle orifice meet the design requirements.