In this paper, we demonstrate a magnetic/mechanical approach for optimizing a miniature self-powered current sensor. The sensor consists of a piezoelectric PZT sheet, CuBe cantilever beam, NdFeB magnet, and mechanical clamp. When the sensor is placed nearby an AC-current carrying wire from a breaker, the magnet fixed on the beam of the sensor experiences an alternative magnetic attractive and repulsive force produced by an AC magnetic field generated by the wire. Due to the alternative magnetic attractive and repulsive force, the magnet fixed on the beam is oscillated. The oscillating beam deforms the PZT sheet and subsequently produces strain in the PZT sheet. Due to the piezoelectric effect, the strain is converted to a voltage response. Through the optimized approach, the voltage output of the sensor is increased from 1.27 volts to 4.01 volts when the sensor is used to detect an AC current-carrying wire of 8 ampere at 60 Hz.