The preparation and formation mechanism of silica/polyvinylpyrrolidone(PVP)-polyacrylonitrile(PAN) coaxial nanofibers were presented in this paper. The PVP-PAN composite nanofibers were obtained via an electrospinning technique, while SiO2 nanoparticles were prepared according to a Stber method. The measurements of water contact angle(WCA), the compared results of silica coating PVP-PAN composite nanofibers with PAN nanofibers indicate that much PVP resided on the composite nanofiber surface, which results in the occurrence of SiO2@polymer coaxial nanofibers due to the formation of hydrogen bonding between silica and composite nanofibers and subsequent adsorption of silica on the fiber surface.