The invention relates to preparation methods of porous carbon from towel gourd vegetable sponge and a composite material of the porous carbon and application of the porous carbon and the composite material in supercapacitor electrode materials. The method for preparing the porous carbon comprises the following steps: (1) washing the towel gourd vegetable sponge, and performing carbonization heat treatment in an atmosphere containing NH3 at a proper temperature; (2) mixing the carbonized product and KOH in a proper proportion, and activating in N2 at the temperature of 750 DEG C. The inner diameter of pore passages of the prepared porous carbon is between 1mu m and 15mu m, the pore wall thickness is between 0.3mu m and 1mu m, and the activated specific surface area can be 1510m<2>/g. The method for preparing the composite material comprises the following steps: reacting the porous carbon with a KMnO4 solution, and growing MnO2 nanosheets, thereby obtaining a porous carbon/MnO2 composite material; or reacting the porous carbon with aniline to obtain a porous carbon/aniline composite material. When serving as the supercapacitor electrode materials, the prepared porous carbon and the composite material thereof have more excellent performance and favorable application prospect compared with a conventional carbon material.