The invention relates to a halogen-free intumescent flame-retardant polypropylene composite and a preparation method thereof. Calculated by weight percentage, the composite comprises 35 to 80 percent of polypropylene, 5 to 30 percent of coated poly-ammonium phosphate, 1 to 20 percent of melamine and the derivatives, 1 to 15 percent of halogen-free macromolecular char forming flame retardant, 0.1 to 5 percent of flame retardant synergist, 1 to 20 percent of rigid inorganic particle, 0.05 to 5 percent of coupling agent, 0.1 to 10 percent of compatilizer, 1 to 20 percent of toughening agent and 0.01 to 4 percent of antioxidant. Compared with the prior art, the material of the invention has good toughness, high strength and environment-protecting flame retardance, and the composite can be widely applied in the fields such as automobile and electronic appliances.