The organic-inorganic complex nano-particles with core-shell structure were synthesized by in situ emulsion polymerization based on fresh slush pulp of calcium carbonate (CaCO3) nanoparticles and acrylate polymer in this paper. The dispersion and encapsulation of nanoparticles were investigated by transmission electron microscopy (TEM). Unplasticized poly(vinyl chloride)(UPVC) was modified by organic-inorganic complex nanoparticles and the effects of toughening and reinforcing were systematically studied. The results showed that the effects of the reinforcement and toughening of organic-inorganic complex nanoparticles on UPVC were very significant. Especially, scanning electron microscopy(SEM) analysis results indicated that large-fiber drawing and network morphologies coexisted in the system of UPVC by joint modification of nanoparticles with CPE.