▎ 摘　　要

NOVELTY - A lightweight composite material comprises 30-90 %mass magnesium alloy powder, and 10-70 %mass graphene material. USE - The lightweight composite material is useful for roof construction including light steel structure, high-rise steel structure, light plate quick-installed residence, frame structure and brick-concrete structure building. ADVANTAGE - The lightweight composite material: can be prepared by a method, which is simple in operation, low in cost, and high in repeatability, and can be carried out industrially on a large scale; has non-flammability, excellent electromagnetic radiation resistance, conductivity, and corrosion resistance, high strength and rigidity, and low density; and adopts magnesium alloy powder, which has high strength, rigidity and heat resistance. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the lightweight composite material, which involves: (S1) configuring the raw material; (S2) adding magnesium alloy powder to an organic solvent (A), uniformly mixing and dispersing to obtain a ball milling liquid (A), and then adding to a cryogenic tank for cooling treatment; (S3) adding graphene material to an organic solvent (B), uniformly mixing and dispersing to obtain a ball milling liquid (B), and then placing in cryogenic tank for cooling treatment; and (S4) adding the cooled ball milling liquid (A) to a ball milling tank for grinding, and then adding the cooled ball milling liquid (B) for grinding.