The invention discloses a preparation method of a three-layer gradient GIS / GIL supporting insulator, which aims at reducing the
electric field intensity of an insulator along a surface or a local region as an optimization target, and solves the optimal
spatial distribution of a
dielectric constant in the supporting insulator by using a
variable density algorithm. According to the optimization result, the
dielectric constant change area is divided into a
dielectric constant transition area and a high dielectric area, the combination contour of the dielectric constant transition area is extracted, and then a hollow dielectric constant transition area with a support and a resin
sprue gate is generated through photocuring 3D printing; a thermocurable high-dielectric
composite material is prepared by adopting a high-dielectric filler /
polymer blending mode, and then the high-dielectric
composite material is poured into the dielectric constant transition area and integrally put into a
metal mold for fixing; and a thermocurable high-dielectric
composite material is prepared in a low-dielectric filler /
polymer blending mode, then the thermocurable high-dielectric composite material is poured into a
metal mold, and the three-layer gradient GIS / GIL supporting insulator can be obtained after curing is completed in vacuum.