The invention belongs to the technical field of modified materials and discloses a low shrink and low density PP material. The material comprises the following components in parts by weight: 85-95 parts of polypropylene resin, 1-5 parts of a polyolefin elastomer, 3-8 parts of a rigid molecular chain material, 1-5 parts of epoxy resin, 0.1-0.5 part of a crosslinking agent, 0.1-0.5 part of an auxiliary crosslinking agent, 0.2-0.4 part of an antioxidant and 0.2-0.4 part of a weather resistant. The invention also discloses a preparation method of the PP material. According to the material provided by the invention, a low molding shrinkage of 0.7-0.9% can be achieved only by adding an extremely small amount of material with large steric hindrance functional rigid molecular chain sections, and meanwhile, the influence on the rigidity and toughness of the PP material is relatively slight; and the material prepared by the method is low in density (smaller than 0.93g/cm<3>), the demand of a light trend is met, and the scratch-resisting performance of the PP material is improved.