Abstract: Compounding or blending is normally considered a good method to produce new polymeric materials for special uses. However, the ductility of polypropylene (PP)/low-density polyethylene (PE-LD) blends is relatively poor. PP/PE-LD microporous samples were prepared via conventional injection molding using water as a blowing agent, and their mechanical properties and microstructure were investigated. The results suggest that the formation of microporous structure enhanced the ductility of PP/PE-LD blends, and their mechanical properties and microstructure were influenced by the compositions of PP/PE-LD blends. A fine microporous structure was observed in the PP-content range of 90 %~50 %, which was attributed to the poor compatibility between the PP and PE-LD phases. This makes the ductility improved much easilier.