The invention belongs to the field of composite materials and particularly relates to a carbon fiber-reinforced resin composite material and a preparation method thereof. Graphene containing an active functional group in the surface is prepared through a modified Hummers method, and a carbon nano tube and the graphene can form a synergistic effect, so that the dispersibility of a nano-scale filler graphene and the carbon nano tube in a resin matrix is greatly improved, and meanwhile, the interface bonding force between the carbon fiber and the resin matrix can be improved due to the presence of the and the graphene and the carbon nano tube. Brominated epoxy resin is capable of improving the flame-retarding characteristic of the composite material; cyanate ester has high strength and reactivity is capable of improving the interface bonding capacity of the epoxy resin and the carbon fiber; and meanwhile, the cyanate ester is taken as a curing agent of the brominated epoxy resin. The carbon fiber-reinforced resin composite material has the advantages of being simple in process, friendly to environment and excellent in property of the composite material.