In order to establish optimal structure for micro vibration due to electric spark occurs in the faulty cable. A novel acceleration sensing with supplement beams structure utilizing the piezoresistive principle is presented and compared with traditional structures. The mechanical model and its simulation solution are built up and carried on, including the calculation of the sensitivity and frequency behavior of several sensor structures. The sensor is built up as an sense beam and supplement beam is supposed to have high sensitivity, higher resonant frequency and minimized lateral effect. For the designed sensor structure, the formula of stress, natural frequency and damping was derived in theory, and the optimized structure is confirmed through adjust the beams size.