Dry transformers are widely used in the field of offshore wind power due to their excellent moisture resistance, salt spray resistance, corrosion resistance, and light transportation and installation characteristics. At present, the insulation materials of dry transformers are mainly epoxy resins. Since the curing reaction between epoxy resin and acid anhydride requires accelerator catalysis, the impact of the introduction of accelerator on electrical performance remains to be explored. Therefore, this paper focuses on studying the influence of the electrophilic accelerator boron trifluoride ethylamine complex on the electrical properties of epoxy resins, prepare epoxy resin samples with different curing times, and conducts volume resistivity and dielectric performance tests at different temperatures. The results show that the electrical performance is greatly affected by temperature and curing time. As the temperature increases, the volume resistivity shows a downward trend, and the dielectric constant and dielectric loss show an upward trend; with the increase of curing time, the volume resistivity increases, and the dielectric constant and dielectric loss decrease, and the difference in electrical performance at high temperatures is more obvious than at normal temperatures.