Effects of 1,3-0-2,4-bis ( 3,4-dimethylbenzylidene ) sorbitol ( DMDBS ) on mechanical properties, optical properties and crystallization behaviors of isotactic polypropylene (iPP) were studied. The results showed that addition of DMDBS could increase the mechanical properties,optical properties and crystallization peak temperature of iPP greatly. When the addition concentration of DMDBS was 0. 2 % , compared to those of virgin iPP, tensile strength and flexural modulus of nucleated iPP could be increased by 7.46 % and 11.96 % , respective...