In order to increase the production of unconventional oil and gas, it is necessary to improve its reservoir. Plasma pulse technology is one of a safe and environmentally friendly reservoir reconstruction technology. In this paper, the discharge test of plasma pulse equipment was carried out in the laboratory. The different discharge stages (pre-discharge, main-discharge, sinusoidal attenuation oscillation and post-discharge stage) of plasma pulse equipment in a single discharge were discussed, and the frequency characteristics in the repeated discharge were studied in detail. The discharge test shows that the energy and average power of main-discharge stage are about 109 J and 15.6 MW respectively, and the discharge frequency range is about 0–25 Hz. Furthermore, the linear attenuation function model of breakdown voltage change under the initial discharge frequency of 4 Hz, 9 Hz, 14 Hz and 19 Hz is established, and the change law of breakdown voltage decreases linearly with the increase of discharge frequency is revealed. The results show that the research content of this paper has an important guiding significance for revealing the variation law of repeated discharge frequency characteristics of plasma pulse equipment, which is helpful to further optimize the design of plasma pulse equipment and improve its working performance.