In order to improve the anti-interference ability, sensitivity and stability of the electric field sensor, a high Q thin-walled liquid-core capillary microcavity combined with the electrophoretic effect is proposed and experimentally demonstrated for the first time. In this paper, whispery gallery mode resonance of liquid-core microcapillary with different diameter and the wall thickness is theoretically simulated and analyzed based on the finite-difference time domain method and that sensitivity increases with decreasing wall thickness is concluded. Microcapillary resonator with diameter of 86 μm, wall thickness of 2 μm and a Q factor of 2.8×10⁶ is fabricated. Using the principle of electrophoresis and the charge of protein molecules, we built an electric field test system. Liquid core microcapillary with different protein solutions achieves the maximum electric field sensitivity of about 10.6 pm/(kV/m).