In this paper, the insulation cylinder of the GIS circuit breaker is taken as the research object. The properties of the insulation cylinder laminated by epoxy resin and aramid fiber are tested and analyzed, including the structure and stratification, Fourier transform infrared spectrum, and dielectric properties. The results show that the relative permittivity of aramid fiber is higher than that of epoxy material at high frequency, and its dielectric loss is higher at low frequency and lower at high frequency, which is different from that of epoxy material. The electric field of the insulation cylinder with epoxy resin and aramid fiber on layers is simulated. Compared with the electric field of a cylinder with pure epoxy, it can be found that the laminated insulation shows a lower maximum field strength. Combined with the mechanical properties of aramid fiber, the laminated structural insulation can replace the traditional pure epoxy material for the insulation cylinder of the GIS circuit breaker, improving insulation performance and stability.