Nano composite polymer electrolytes based on poly (vinyl alcohol) PVA as host polymer, ammonium hexafluoro phosphate (NH4PF6) as salt and zirconium di oxide (ZrO2) as nano-filler have been prepared by Solution Casting Technique. Admittance analysis shows that the addition of the nano-filler ZrO2 the polymer electrolyte enhances the amorphous phases of polymer matrix which in turn increases the ionic conductivity. 0.03g ZrO2 added polymer electrolyte has maximum ionic conductivity 3.029 × 10-3 Scm-1 at ambient temperature. The weight loss for ZrO2 added an electrolyte is less compared to pure polymer electrolyte suggesting that the thermal stability of composite polymer electrolyte system has been improved due to the addition of the nano-filler ZrO2. The optical band gap decreases from 3.68eV of nano-filler undoped polymer electrolyte to 3.21 eV of nano-filler incorporated polymer electrolytes.