The invention discloses a multicomponent halogen-free flame-retardant master batch which is prepared by the following raw materials in parts by weight: 1-25 parts of graphene, 20-70 parts of halogen-free flame retardant, 0.5-1 part of antioxidant and 5-40 parts of carrier. The invention further discloses a preparation method of the multicomponent halogen-free flame-retardant master batch and the preparation method comprises the following steps: weighing the raw materials, mixing at a high speed, performing fusion compounding in an extrusion machine, pelletizing and the like. The master batch is high-efficiency, halogen-free and flame-retardant, and good in thermal stability, has an excellent dispersion effect in a polymer matrix, the flame-retardant property and mechanical performance of a composite plastic material can be effectively improved, and the problem that a carbon layer generated by the traditional IFR is poor in compactness and bad in thermal stability and affects the mechanical performance of the material can be solved; the method provided by the invention solves the problems that the graphene-containing multicomponent composite master batch is difficult to feed and is dispersed unevenly, the compatibility between the master batch and the resin matrix can be improved, and the major difficulty of the preparation of the graphene-containing multicomponent composite flame-retardant master batch can be solved.