PAMPS/MMT composite electrolytes with high ionic conductivities were prepared by solution-casting method. The influences of Na-MMT contents on the ionic conductivities and mechanical properties of PAMPS hydrogel electrolyte were characterized and the electrochemical properties of supercapacitor with PAMPS/MMT composite electrolytes were investigated. The addition of Na-MMT can increase the ionic conductivities, tensile strength of PAMPS. PAMPS/MMT composite electrolyte has the superior integrated performance of ionic conductivities and tensile strength when the mass fraction of Na-MMT is about 5~7%, the ionic conductivity is 5.91×10 -2 S cm -1 and the tensile strength is 8.9 MPa. The capacitor exhibits ideal behavior for the electronic double-layer capacitance. The specific capacitance and the cycling stability of PAMPS/MMT composite electrolytes are enhanced in comparison with that of PAMPS. Thus it provides a promising composite polyelectrolyte for supercapacitor.