Due to the many types of 10 kV distribution network line crosssectional area, when the non-contact voltage device measures the voltage of different line diameters, it will cause the line-electrode coupling capacitance time-varying, resulting in the difficulty of determining the voltage dividing ratio, and unable to accurately invert the line voltage. In this paper, under the condition that the outer copper electrode is not grounded, the self-calibration method of du-al-probe coupling capacitance based on the capacitance-switching array is proposed, which eliminates the influence of line-diameter variation on the measurement results by casting the capacitance between the inner and outer copper electrodes of the dual-probe. Secondly, the sensitivity formula of each measured voltage is derived to quantify the effect of measurement error on the inverted line voltage, and the optimized probe parameters are used to realize the adaptive measurement of the distribution network line diameter. Finally, the simulation circuit is designed and the experimental platform is constructed to complete the calibration of the sensor parameters and the adaptive testing of different line diameters. The experimental results show that when the cross-sectional area of the 10 kV distribution line changes from 70 mm2 to 150 mm2, the maximum relative error between the line voltage inverted by the sensor and the real line voltage is 2.685%, which meets the standard of electronic voltage transformer, which in turn can verify the effectiveness of this method.