The invention discloses a graphene modified fiber reinforced resin-based composite material which is prepared by performing surface treatment on reinforced fiber by using a graphene fiber surface treating agent, and by compounding the reinforced fiber after surface treatment with thermosetting resin and thermoplastic resin, wherein the graphene fiber surface treating agent is prepared by mixing a silane coupling agent with graphene; the graphene comprises one or a mixture of more of single-layer graphene, multi-layer graphene and graphene oxide; the silane coupling agent is one or a mixture of more of a methyl vinyl silane coupling agent and an amino silane coupling agent. The graphene modified fiber reinforced resin-based composite material and a preparation method thereof, which are disclosed by the invention, have the beneficial effects that the interface shearing strength of the fiber reinforced resin-based composite material is effectively improved, the mechanical property of the fiber reinforced resin-based composite material is improved, the service life of the fiber reinforced resin-based composite material is prolonged, and a great significance in study, application and popularization of the fiber reinforced resin-based composite material can be achieved.