▎ 摘　　要

NOVELTY - Composite material comprises polyimide, foaming agent, vitrified micro-beads and graphene sheet, where density of composite material is 50 gram per centimeter cubed, and damping coefficient is not less than 0.3 at 250 degrees C. USE - Composite material used for naval ship, aircraft and train. ADVANTAGE - The composite material cost-effective, saves fuel, and improves speed, heat insulating property and safety. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing composite material, which involves: (A) adding polyamic acid, graphite, nanometre carbon fiber, vitrified micro-beads, foaming agent and silicon oil in a reaction vessel at 160-180 degrees C, (B) stirring the obtained product slowly; (C) stirring the obtained product quickly for 8 minutes uniformly; and (D) adding the obtained product in a mold to obtain composite material.