Polypropylene (PP) is an environmentally friendly cable insulation material with relatively great insulation properties and has the advantages of being recyclable as a thermoplastic material. PP is easy to brittle fracture due to its poor toughness at low temperatures. Hence,it is necessary to improve the toughness of PP. In this paper,three modified PP samples are studied,namely PP blended with 10% mass fraction of polyolefin elastomer(POE),PP blended with 10% mass fraction of styrene ethylene butylene styrene (SEBS),and copolymerization modified PP specimen synthesized with PP as matrix and polyethylene (PE) in the reactor. The PP samples before and after modification are tested to obtain their physical properties,chemical properties,mechanical properties and electrical properties. It is concluded that the toughness,tensile strength and elongation at break of PP increase after the modification,while the melting temperature decreases and the dielectric loss increases. For the modification methods,the initial melting temperature and AC breakdown field strength at 20-80 ℃ of the copolymerization modified PP specimen are higher than those of the blending modified PP specimens. Instead,the blending modified PP specimens have better mechanical properties and lower dielectric loss at high temperature than the copolymerization modified PP specimen does. After comprehensive consideration,the copolymerization modification may be more suitable to enhance the toughness of PP than the blending modification.