The facilitated transport membranes with sulfonated poly(ether ether)ketone (SPEEK)- AgNO3 is based on complexes between silver ions and olefin, these membranes were prepared and tested for separation of olefin/paraffin. The facilitated transport membranes showed high selectivity of isoprene over n-pentane and long-term stability. Depending on various reaction conditions, the degree of sulfonation (DS) of SPEEK was measured by 1H NMR spectroscopy. In the membranes containing SPEEK-AgNO3, the performance of the membranes was affected by the DS of SPEEK. As the DS of SPEEK was increased, the selectivity of isoprene over n-pentane was increased and the stability of that was continued.