Abstract: Use polypropylene(PP) as the matrix, ethylene-octene copolymer(POE) elastomer and styrene-ethylene/butylene-styrene triblock copolymer(SEBS) as fillers, the elastomer/polypropylene composite is prepared by two mixing methods of twin screw extruder and torque rheometer. Studies show that the mechanical toughness of elastomer/polypropylene composites is improved compared to pure PP, but the electrical strength of the material reduces, and the accumulation of space charges increases. Among them, SEBS/PP composites have the best mechanical toughness and the highest electrical strength. The shear stress of the twin screw is stronger, so the material elastomer prepared by its mixing is more uniform, the crystallinity increases, and the electric strength increases. But at the same time, stronger shear stress will also degrade PP macromolecular chains, leading to increased space charge accumulation.