Real-time and accurate voltage measurement data is the basis for constructing a transparent power grid. The non-contact measurement technology has the advantages of safety, convenience and low cost, and has become a realistic basis for widespread deployment. A flexible voltage probe based on the principle of capacitive coupling is designed in this paper, and the sampling circuit’s impact on the probe voltage division is analyzed, and a method using 2 probes to figure out the wire voltage to be measured utilizing the different output is proposed. The simulation and experimental results show that the proposed method can measure the wire voltage without damaging the insulation sheath. In laboratory environment, the amplitude measurement error of steady power frequency voltage is less than 2%, and the phase measurement error is less than 0.2 °.