In order to solve the problem of low melt strength and narrow foaming window of polypropylene (PP) based wood plastic composites, branched PP was used as matrix, the melt viscoelastic modification was carried out using polyolefin elastomers (POE) and low molecular weight microcrystalline wax. The molecular motion characteristics of the material in different hybrid systems and the pore morphology parameters under different process conditions were explored in order to achieve the microporous preparation of PP based wood plastic composites. The results show that compared to the “ lubrication ” effect of low molecular weight microcrystalline wax, POE can significantly improve the melt strength by constructing interpenetrating network structure with PP. By adjusting the foaming temperature and screw speed, its pore size and distribution density can be controlled to 71.4 μm and 2.68×10⁴ cm^-3, respectively, achieving a transition from “large and sparse” pore structure to “small and dense” microporous structure.