The invention discloses a warm mix polymer modified asphalt mixture and a preparation method thereof, wherein the mixture comprises 4.0-6.0 parts of a warm mix polymer modified asphalt, 1.0-3.0 parts of ore powder, and 91.0-95.0 parts of an aggregate, the warm mix polymer modified asphalt comprises 1-7 parts of a warm mix agent, 2-5 parts of a polymer, 88-97 parts of matrix asphalt, and sulfur, and the sulfur accounts for 0.01-0.07% of the total mass of the warm mix agent, the polymer and the matrix asphalt. The warm mix agent preparation method comprises: under the effect of a catalyst, carrying out a reaction on a macromolecule alkane and a halogen to obtain an intermediate; obtaining an aromatic hydrocarbon complexing component from aromatic hydrocarbon oil and a complexing compound under the effect of a catalyst; and introducing the aromatic hydrocarbon complexing component into the intermediate, carrying out a reaction, and aging to obtain the warm mix agent. According to the present invention, by adding the warm mix agent to the asphalt in the mixture, the warm mix effect is provided for the asphalt, the high temperature performance and the low temperature performance of the asphalt are considered, the thermal stability of the asphalt is improved, the aging resistance is improved, the thermal aging of the asphalt is reduced, and the harmful gas generation is reduced.