A new route to prepare CaCO3 nanoparticles/polyvinylpyrrolidone (PVP) nanofibers is reported. An aqueous solution of K2CO3 was added to a solution of CaCl2/PVP, resulting in in-situ preparation of CaCO3 nanoparticles. Then composite nanofibers containing CaCO3 nanoparticles were successfully prepared by electrospinning. The morphology of the resulting composite nanofibers was characterized by field-emission scanning electron microscopy. In addition, the products were characterized by thermogravimetry analysis and Fourier transform infrared spectra.