A LiNbO3-based integrated optical sensor with Mach-Zehnder optical waveguide interferometer and tapered antenna array was designed and fabricated for electric field detection. Experimental results reveal that this sensor has a frequency response deviation less than ±10dB in the range of 10kHz~18GHz, and its minimum detectable electric field intensity reaches 0.4V/m. Moreover, a pulsed electric field with nanoseconds width and electric field intensity of 103V/m was realized.