Abstract: In order to improve the performance stability of epoxy resin casting insulation parts, the differences in the development of temperature and curing degree in the curing process of epoxy resin systems with the same components and small differences in the dosage of curing agent were studied. The curing dynamic model of epoxy resin was established by DSC experiment. The finite element simulation model of curing process of epoxy resin casting insulation was established by coupling temperature field and curing degree field. The development of curing temperature and curing degree of epoxy resin with different formulas was calculated and compared. The results showed that: Under the same curing process, the epoxy resin casting insulation parts with little difference in formula have obvious differences in the curing process, the maximum temperature difference is 5.21K, the maximum curing degree difference is 0.348, and the temperature and curing degree at the same curing moment do not increase with the increase of curing agent content, which indicates that the small change in the formula will lead to unpredictable differences in the curing process.