In the field of lightning protection in power systems, improving the accuracy of primary side lightning overvoltage inversion and reconstruction of capacitive voltage transformers (CVTs) is of great significance. Therefore, this article innovatively proposes a lightning overvoltage inversion method based on the CVT black box inverse model. In the research process, firstly, scattering parameter measurement technology is used to accurately obtain the frequency domain response characteristics of CVT in the frequency range of 0.1 Hz–10 MHz, and the vector matching method is used to construct its voltage transfer positive function and analytical inverse function; Secondly, based on the voltage waveform data of the CVT secondary side distortion measured on site, corresponding algorithm programs are written according to the inverse function to achieve accurate inversion and reconstruction of the primary side lightning overvoltage waveform. Experimental verification shows that this method significantly improves the inversion accuracy, with the measured peak error of lightning impulse wave greatly reduced from 20.7% to 1.52%, and the peak error of standard lightning impulse voltage reduced from 136.7% to 9.89%. This provides strong data support for insulation design of power equipment and lightning protection evaluation of transmission lines.