The invention relates to a polypropylene material and a preparation method thereof, in particular relates to a halogen-free flame-retardant polypropylene micro foaming material and a preparation method thereof, and belongs to the technical field of polymer materials. The halogen-free flame-retardant polypropylene micro foaming material comprises the following raw materials in parts by weight: 50-70 parts of polypropylene, 1-5 parts of a compatilizer, 5-20 parts of a filing agent, 0.5-5 parts of foaming agent master batches, 2-8 parts of an organic silicon flame retardant, 15-25 parts of an expansion type flame retardant and 0.2-2 parts of an antioxidant. The halogen-free flame-retardant polypropylene micro foaming material has the beneficial effects that a compounding synergistic flame-retardant technology of the organic silicon flame retardant and the expansion type flame retardant is adopted, the thermal stability of the expansion type flame retardant during the processing of a composite material is improved, and the compatilizer is adopted to ensure that the dispersive and interfacial bonding of the flame retardants in a polypropylene matrix is improved; and by adopting an injection micro foaming technology, the halogen-free flame-retardant polypropylene micro foaming material with a lightweight characteristic is obtained, the flame-retardant grade reaches UL94-V0 level, and the application range of the polypropylene micro foaming material is broadened. The halogen-free flame-retardant polypropylene micro foaming material can be used in the fields of electric tools, electronic and electrical appliances, automobiles, buildings, packaging, shipbuilding and the like.