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Thermal barrier coatings (TBCs) are used to provide thermal insulation for superalloy components from high-temperature gas streams. Due to the insulativity of the top coat and the different physical and chemical properties of each layer, it is difficult to machine small holes in TBC-coated components. In this paper, electrical discharge machining (EDM) was used to machine small holes in high-velocity oxy-fuel-sprayed TBC-coated nickel superalloys using the assisting electrode method. The signal-to-noise (S/N) ratio of the experimental results was used to study the influence of the processing parameters on the response characteristics. Based on the S/N ratio results, the machining parameters of multiple responses were optimized using the gray relational analysis method. Experiments were conducted using an orthogonal array, and the factors selected in this study were peak current, pulse duration, duty factor, and flushing pressure. The responses (i.e., machining time (MT), electrode wear (EW), maximum falling distance of 8 %YO-stabilized ZrO (MFD-YSZ), and surface roughness (Ra)) were chosen to evaluate the effects of machining. The results showed that peak current influences MT, EW, Ra, and MFD-YSZ more than the other factors and that pulse duration is the most significant factor for multiple responses. A confirmation experiment showed that the optimal process parameters improved the gray relational grade index for the multiple responses from 0.7393 to 0.7785. [ABSTRACT FROM AUTHOR]