The invention relates to a high-melt-strength polypropylene material and a preparation method thereof. The method comprises the following steps: carrying out mixing and granulation on homopolymerized polypropylene, copolymerized polypropylene, unsaturated silane monomers, a stabilizing agent and other additives in a parallel twin-screw extruder; carrying out irradiation on the obtained mixture by using high-energy electron rays; and then, carrying out heat treatment on the mixture so as to obtain the high-melt-strength polypropylene material. According to the invention, a preparation process is green and pollution-free, the structure of the material is controllable, and a product has no peculiar smell; and the high-melt-strength polypropylene material and preparation method thereof disclosed by the invention can be applied to the fields of foaming molding, thermoforming and the like.