Abstract: To investigate the effects of residual micro-burrs induced by mechanical drilling on the flow rate of fuel nozzles, a flow simulation model for the fuel nozzle of aero-engine was established. The Realizable k-ε turbulence model is adopted to analyze the influence of micro-burrs distribution position on the flow characteristics in the flow hole. The results reveal that the micro-burrs would generate negative pressure in the downstream region of the inlet owing to their edge-corner features. This alters the pressure and flow-velocity distributions inside the flow passage and consequently degrades flow-rate consistency. To eliminate the adverse effect of residual micro-burrs, micro-electrical discharge machining (micro-EDM) was employed to fabricate flow holes with high quality, yielding uniform distribution of pressure and flow velocity. Flow test results demonstrate that micro-EDM-processed fuel nozzles exhibit excellent flow-rate consistency, with a relative error below 1.0%, and the flow rate of each nozzle falls within the allowable tolerance range. Furthermore, the flow measurements of two typical fuel nozzles of two additional specifications (orifice diameters of 0.81 mm and 1.21 mm) further verified the improvement effect of flow-rate consistency achieved by the micro-EDM technique.