The large-scale access of distributed generation and nonlinear power electronic equipment in the new power system has brought about increasingly significant power grid harmonic problems. The existing ultra / ultra-high voltage power grid voltage transformers are limited by the frequency band and are difficult to accurately reflect the power grid harmonic characteristics. In this paper, a grid voltage reconstruction method based on the leakage current of capacitive equipment is proposed. Firstly, the high-frequency simplified model of capacitive equipment is established, and the equivalent model parameters are obtained by the high-frequency and high-voltage dielectric parameters of equipment and GA-LM optimization algorithm. Based on the equivalent model, the transfer function between leakage current and grid voltage is further deduced. Finally, the reconstruction method verification platform is built, The feasibility and accuracy of the method are verified by simulation and experiment.