Abstract: In order to investigate the spinnability and processing performance of the photocatalytic functional polypropylene (PP) fiber, SiO₂ coated modified nano-TiO₂ particles (SiO₂@TiO₂) were used as additive and PP was modified by blending firstly. Then, the extensional rheological properties of SiO₂@TiO₂/PP blend melts were tested by capillary rheometer, and the influences of SiO₂@TiO₂ on the properties of PP were studied by XRD and DSC. The results demonstrate that the SiO₂@TiO₂/PP blend melts belong to the fluids of extensional thinning type. With the increasing of temperature, both of the extensional stress and extensional viscosity of melts decrease; extensional viscosity increases with the increasing of additive amount, and extensional flow activation energy reduces with the increasing of extensional strain rate. The addition of SiO₂@TiO₂ does not change the crystalline structure of PP significantly, but enhance the performance of crystallization. When the content of SiO₂@TiO₂ is 4wt%, the crystallinity of the blend melt is 8.6% higher than that of pure PP. SiO₂@TiO₂ leads PP to form more compact crystal structure, which has important influences on the properties of materials.