For the application of capacitance-coupled non-contact voltage measurement, the coupling capacitance between probe and wire is affected by wire diameter, wire insulation material and relative position deviation. It is difficult to determine the voltage division relation and the voltage cannot be reconstructed. In this article, a self-calibration method of non-contact voltage measurement based on impedance transformation is proposed to realize the self-calibration of sensor gain in practical measurement. Firstly, the basic principle of capacitive coupling voltage measurement is introduced, from which the problems exist and the self-calibration method based on impedance transformation is proposed. Then, the influence of calibration accuracy on system parameters is analyzed by simulation and the principle of parameter selection is given. On this basis, the sensor probe and the circuit topology are developed. Finally, the accuracy test, anti-interference ability test and scene adaptability test of the sensor prototype are carried out. The accuracy test shows that the maximum relative error of voltage amplitude is 0. 59% , and the phase relative error is 0. 76% . The anti-jamming ability test shows that the coaxial probe has good shielding effect on the surrounding coupling electric field. The scenario adaptability test shows that the maximum relative error is 1. 24% when different types of circuits are tested.