The invention discloses an injection molding machine for automotive interior parts and a preparation method for the automotive interior parts. The injection molding machine comprises a bicolor vertical injection molding machine, wherein a compression molding mold and an injection mold are arranged in the bicolor vertical injection molding machine, wherein the compression molding mold is used for spreading an injection molding part into the injection mold, the injection mold comprises an upper mold and a lower mold, the middle part of the upper mold is provided with a bulge, the bulge is provided with an injection molding part forming cavity, four corners of the upper mold are respectively provided with a buckling pin, and the side edge of the upper mold between two adjacent buckling pins is provided with a buckling boss; the middle part of a lower plate body is provided with a lug boss for storing the injection molding part, and the lug boss is matched with the injection molding part forming cavity; the upper mold and the lower mold are in a closing state, and the automotive interior part can be formed in the injection molding part forming cavity. The injection molding part is arranged on the lug boss, so that the automotive interior part can be formed by closing the upper mold and the lower mold, and the production efficiency and consistency of the automotive interior part can be improved.