The invention relates to a polypropylene resin foam concentrate and a preparation method thereof. The foam concentrate is prepared by taking irradiation modified polypropylene resins as basic raw materials through the steps of adding additives such as a chemical foaming agent, a nucleating agent and a lubricant and the like into the basic raw materials, and uniformly mixing the mixture in a high-speed mixer; and then, adding the obtained mixture into a tandem extruder to carry out extrusion and granulation, thereby obtaining the polypropylene resin foam concentrate. The polypropylene resin foam concentrate provided by the invention can be applied to the extrusion of polypropylene foamed sheets, foamed pipes and foamed profiles; the polypropylene resin foam concentrate is high in modulus of foaming products, good in heat resistance, uniform in foaming hole, and adjustable in density, thereby opening up a new way for the extrusion and foaming of polypropylenes.