The invention relates to a polypropylene composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The polypropylene composition is prepared from the following raw materials in parts by weight: 40 to 80 parts of polypropylene resin, 1 to 7 parts of nano-montmorillonite and 3 to 15 parts of a compatilizer, wherein the compatilizer is SEBS-g-GMA. According to the preparation method disclosed by the invention, by selecting the nano-montmorillonite and the compatilizer SEBS-g-GMA, the montmorillonite is sufficiently strippedand dispersed, and the compatibility between the montmorillonite and a polypropylene matrix is enhanced; the polypropylene/montmorillonite composite material is strengthened and toughed by utilizing the nano-montmorillonite. The polypropylene composition disclosed by the invention has the characteristics of low density (light weight), high rigidity and high toughness; the polypropylene compositioncan be used for preparing interior and exterior trim parts of automobiles and achieves the aim of weight reduction.