The invention discloses a quaternary composite carbon conductive agent, which mainly comprises carbon black, carbon nano-fibers, graphite and quasi-two-dimensional nano carbon. The preparation method of the quaternary composite carbon conductive agent mainly includes the steps: mixing the carbon black and the graphite to form carbon-containing mixture and performing microwave discharge under the protection of nitrogen to generate a conductive agent head product with parts of the carbon nano-fibers; adding dispersing agents, adhesives and solvents into the conductive agent head product to perform wet stirring and ball milling; and obtaining the quaternary composite carbon conductive agent. The quaternary composite carbon conductive agent has the advantages of high conductivity, large specific surface area, high purity, high dispersibility, low addition ratio and the like, the conductivity is higher than 10S/cm, the specific surface area can reach 40 (m2/g), the ash content is lower than 0.02%, and the addition ratio can be generally smaller than 2%. The quaternary composite carbon conductive agent has excellent conductivity, can be sufficiently dispersed in an electrode and can be used for a high-performance battery.