To enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance results in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.