The invention belongs to the field of composite materials, and particularly relates to a rubber-plastic composite material and a preparation method thereof, wherein the rubber-plastic composite material is prepared from the following raw materials by weight: 50-90 parts of a rubber, 5-30 parts of polypropylene, 2-20 parts of a polybutene alloy, 5-30 parts of a filler, 0-5 parts of an antioxidant,and 0-5 parts of a light stabilizer, wherein the polybutene content in the polybutene alloy is 60-95%, the propylene content in the polybutene alloy is 4.9-35%, and the polybutene-polypropylene blockcopolymer content in the polybutene alloy is 0.1-5%. According to the present invention, by adding the filler and the specific polybutylene alloy to the rubber and the polypropylene, the obtained rubber-plastic composite material has excellent rigidity, excellent heat resistance and excellent toughness; and the experimental results show that the rubber-plastic composite material has the Shore D hardness of more than 60, the bending strength of more than 500 MPa, the heat distortion temperature/Tff0.45 of more than 70 DEG C, and the notched impact strength of more than 10 kJ/m<2>.