CaCO3 nanoparticles synthesized from CaCl2 and Na2CO3using a new, simple and fast technique. Factors affecting on the particle size such as concentration of Ca 2+ and CO3 2-, PEG weight dissolved in Ca 2+ solution, flow rate, temperature, media type, PEG weight dissolved in the used medium, concentration of CO3 2-, stirring speed, medium volume and additive dissolved within Ca 2+ solution investigated. The obtained particles were characterized by SEM, XRD, EDS, IR and TGA. The characterization clarified that the particles prepared were spherical with size range of 19-30 nm, ultra-pure and the crystal was calcite. Moreover, the preparation system was redesigned to be continuous preparation system. The histogram showed that the CaCO3 nanoparticles obtained were homogenous in size (30 nm). Finally, the obtained nanoparticles were used in preparation of nanoporous PVC film with pores size range 80-120nm