Abstract: Maleic anhydride (MA) was grafted onto polypropylene (PP) using a composite initiator of dicumyl peroxide/benzoyl peroxide, which was used as a compatibilizer in a composite of PP/PA6/ organnomontmorillonite (OMMT). The effect of contents of the compatibilizer and OMMT on the mechanical properties of the composite was studied. A supercritical CO2 dynamic microcellular setup was used to research the foaming properties of the composites including foaming temperature, rotor rate, and vibration force. It showed that compared with neat PP, the melt strength, impact strength, and tensile strength increased by 163 %, 41 % and 8.4 %, respectively. By superimposing a vibration field on the shear stress field, the distribution of cells was homogenized and the density of cells was increased.