▎ 摘　　要

NOVELTY - An insulating composition comprises graphene nanosheet and a layered composite metal hydroxide. The volume ratio of graphene nanosheet to layered composite metal hydroxide is 0.025-0.1 vol.%. USE - Insulating composition is used in production of composite material used for preparing insulation material for direct-current ultrahigh-voltage power transmission line (all claimed). ADVANTAGE - The flame retardant composite material containing the composition has excellent mechanical characteristics, tracking resistance and electric corrosion resistance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) production of the insulating composition, which involves dispersing the graphene nanosheet into a solvent by ultrasonic dispersion, adding the divalent and trivalent metal salt or oxide of the layered composite metal hydroxide and stirring, introducing the mixture into a ball mill for wet grinding, drying the resultant product, subjecting the dried material to dry milling in a ball mill, and optionally dry milling the resultant mixture along with a coupling agent; (2) use of the insulating composition during the fabrication of an ultra high voltage, direct current transmission line insulation device; and (3) insulating composite material for ultra high voltage direct current, which contains the insulating composition for ultra high voltage direct current and a polymer matrix.