An integrated optical E-field probe with the segmented electrode using LiNbO3 Mach-Zehnder (M-Z) waveguides is proposed and an equivalent circuit of the segmented electrode is given. According to the circuit theory, the electrode structure of the probe is designed. The unpackaged size of the fabricated probe is as small as 60*6*0.5 (mm). The measured results show that the half wavelength voltage is 7.7 V, the +-5 dB baseband range is 3 GHz, and the minimum detectable field is lower than 90 dB*microV/m (bandwidth 100 Hz). Therefore it can be used in the electromagnetic compatibility (EMC) measurements.