Abstract: Integrating the processes of preparation of nano-sized CaCO₃ and its surface-coating，CaCO₃/SiO₂ core-shell nanoparticles were prepared by sol-precipitation method using sodium silicate as silica source.A layer of dense silica membrane was coated on the surface of nano-sized calcium carbonate.Size，morphology，chemical composition，structure，and surface properties of the composite nanoparticles were characterized by TEM，FT－IR，TG，XRD，BET，and oil absorption measurement etc..As the CaCO₃/SiO₂  nanoparticles were applied in SBR vulcanizate，the tensile strength and tearing strength of SBR vulcanizate were improved remarkably.When the filling amount of the CaCO₃/SiO₂  nanoparticles was 75 phr，the SBR vulcanizate had the maximum tensile strength（13.6 MPa）.

Key words: nano-sized CaCO₃, CaCO₃/SiO₂ nanoparticles, core-shell structure, SBR vulcanizate