Tube electrode high-speed electrochemical discharge machining (TSECDM) has been effectively used in the manufactures of micro holes with difficult-to-cut conductive materials in the field of aerospace industry. The design and parameters of circuit are critical for the machining performances of TSECDM. In this paper, the influences of circuit on the TSECDM performances are studied. Firstly, a relaxation type RLC generator is designed and analyzed by MATLAB simulation. Secondly, the effects of RLC circuit parameters such a resistor (R), capacitor (C) and inductor (L) on machining performances are investigated by experiments on the bulk of SS304 alloys by limiting factors changing. Finally, the analysis achievement indicated that the circuit selection parameters value R (15Ω); C (220nF); L (0.13mH) can be used to obtain a better machining performance.