Abstract: Amorphous cobalt boride alloy-reduced graphene (CoB-RGO)/cotton fabric flexible composite electrodes were prepared by impregnation-drying method and chemical reduction method at room temperature and atmospheric pressure. The effects of Co²⁺ concentrations on the structural morphology and electrochemical properties of CoB-RGO/cotton fabric flexible composite electrodes were studied. The results show that amorphous CoB presents an open 3D sheet structure interlaced with each other when the concentration of Co²⁺ is 0.14 mol/L. Compared with amorphous CoB/fabric and RGO/fabric composite electrodes, amorphous CoB-RGO/fabric composite electrodes show the better electrochemical properties. With the current density of 0.25 mA/cm², the specific capacitance of amorphous CoB-RGO/cotton fabric composite electrodes is up to 218.8 F/g. There is no obvious effect of folding times and folding angles on the electrochemical performance of CoB-RGO/cotton fabric composite electrodes, which indicates their good flexibility.