The invention relates to the field of electrode materials for all-vanadium redox batteries (VRB), in particular to a preparation method of a high-performance graphene modified carbon felt applicable to the all-vanadium redox battery, and solves the problems of low conductivity, low specific surface area, low electrochemical activity, low vanadium ion pair catalysis performance, low single-batteryperformance, high cost and the like of a commercial carbon felt for a vanadium battery at the present stage. The graphene modified carbon felt is prepared from the commercial carbon felt by using a chemical vapor deposition (CVD) method. The composite carbon felt prepared according to the preparation method disclosed by the invention is high in conductivity, high in specific surface area, high inelectrochemical catalysis performance, excellent in chemical stability, good in VRB battery performance and low in cost. The preparation method disclosed by the invention has the advantages of simpleoperation, feasibility, low product cost, favorability for industrial production, environmental friendliness and the like, and can be widely applied to the field of VRBs.