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Turbine blades of aero engines often require small-size and high depth-diameter ratio holes, which have been a promising method for film cooling under harsh working conditions of both high temperature and pressure. However, for the film cooling holes with different spatial angles, existing methods are difficult to eliminate sharp corners that might be damaged easily due to stress concentration and thus reduce the strength of turbine blades. Herein, electrochemical machining (ECM) method based on insulated electrodes was proposed to round the sharp corners of film cooling holes on the GH4169 plate. Electrochemical rounding theory was analyzed in detail. Tube electrodes were insulated by polyimide capillary tube to reduce the stray corrosion and improve the precision and strength of turbine blades. In addition, the size of rounded corners could be adjusted by changing the processing parameters including processing voltage, processing time, processing gap, electrode descent position, and electrode exposure length. This electrochemical rounding process can round the film cooling holes efficiently, and is expected to be applied in the field of aviation manufacturing widely. [ABSTRACT FROM AUTHOR]