A method for manufacturing an electrode of a supercapacitor is provided. First, a poly(acrylonitrile) (PAN) fabric is provided. The PAN fabric includes a plurality of PAN fibers each having a diameter of about 50-500 nm. Then, the PAN fabric undergoes a heat treatment so that the PAN fibers are carbonized to form a carbon fiber textile. The carbon fiber fabric includes a plurality of carbon fibers each having a diameter of about 50-500 nm. The surface of each carbon fiber is nano-porous having a plurality of nano pores of about 1-50 nm in diameter. The total surface area of the nano pores account for about 85-95% of the total surface area of the carbon fibers. The carbon fiber fabric is then cut to acquire the electrode of the supercapacitor.