The aim of the present work is to subject the polyelectrolyte solutions of nylon-6 in formic acid undergoes an electrospinning process. To form sub-nanofibers (<50 nm in diameter) within the electrospun nanofibers mats, polymer concentration, applied voltage, solution temperature and environmental condition were chosen as variables. Scanning electron microscope was used to probe the presence of sub-nanofibers into the electrospun mat. To appear sub-nanofibers significantly, during the process of electrospinning, an optimum condition was obtained by finding a proper concentration of solution, applied voltage and temperature of solution which were 15 wt.%, 22 kV and 25 degrees C, respectively.