The invention relates to the field of functional composite materials, in particular to an ultra-high molecular weight polyethylene-graphene-nickel composite material with a high electromagnetic shielding performance and a preparation method. Composite materials used for preparing the composite materials are nickel-plated graphene-coated ultra-high molecular weight polyethylene particles taking metallic nickel as a shell structure and taking graphene-coated ultra-high molecular weight polyethylene particles as a core, wherein the content of the graphene-coated ultra-high molecular weight polyethylene particles ranges from 97.42 vol% to 98.91 vol%, the content of metallic nickel ranges from 1.09 vol% to 2.58 vol%, and the content of graphene in the composite material is at least 0.028 vol%. By preparing the composite material with the isolation structure, on the condition that the content the metallic nickel and the content of the graphene are extremely low, the electric conductivity and electromagnetic shielding performance of the composite material can be significantly improved, and the purposes of the high electric conductivity and the high electromagnetic shielding performance of the composite material are achieved.