The present invention disclosed a method to fabricate a novel thermoelectric polymer membrane comprising processes of fabricating a polymer membrane with scaffolded-nanofiber by using electrospinning technique, preparing an ionic liquid electrolyte solution and fabricating a thermoelectric polymer membranes by immersing the polymer membrane into the electrolyte solution to trap the ionic liquids electrolyte into the polymer membrane. The thermoelectric polymer membrane fabricated according to the present invention possesses high electrical conductivity, low thermal conductivity and high Seebeck coefficient which are very suitable to be used in thermoelectric devices, fuel cells, battery cells, solar cells, and similar embodiments.