<p>For electrochemical discharge machining (ECDM), the thickness and stability of the gas film formed on the tool electrode surface act as key factors that directly affect machining efficiency and precision. To resolve this important issue, this study suggests a novel method for ECDM-based processing of zirconia ceramics, one that adopts a rotating porous electrode fitted with an internal gas supply system. This method uses a special porous metal material with micron-scale pore characteristics as the tool electrode, through whose pore channels auxiliary gas is delivered from the electrode bottom to the machining area in an “internal supply” mode to achieve inter-electrode gas compensation. Compared with traditional solid electrodes, the porous structure not only helps form a thinner and more uniform insulating gas film but also effectively solves the problem of excessively large residual material core in traditional solid electrode machining, thereby synergistically improving machining precision and efficiency. First, this study conducts Fluent fluid simulation. The simulation results show that under internal gas supply conditions, the pressure is the highest at the edge of at the edge of the inlet area of the porous electrode’s inlet area, whereas the highest pressure appears at the center of its outlet area; the velocity distribution is characterized by uniformity at the inlet and high velocity at the edge but low velocity at the center of the outlet. Subsequently, via single-factor experiments, the influence rules of machining voltage, gas supply flow rate, electrode rotation speed, electrolyte temperature, and machining time regarding the material removal rate (MRR) as well as the machining morphology for zirconia ceramics is analyzed quantitatively. The experimental results demonstrate that with the optimal internal gas supply condition, the proposed method achieves a 31.3% increase in machining depth and a 12.7% increase in MRR with simultaneously improved machining quality.</p>