NOVELTY - The linear crystalline carbon nanofibers (200) and the acetylene black (100) are mixed in a predetermined mixing ratio to form a slurry. A platinum-supported catalyst/a platinum alloy-supported catalyst is prepared by adding sodium hydroxide (NaOH), a platinum precursor or a platinum alloy precursor, and the mixture of linear crystalline carbon nanofibers and acetylene black to a solvent for catalyst synthesis, and refluxing at a temperature of 140-180 degrees C. to reduce the alloy precursor or the platinum alloy precursor.    USE - Method for preparing catalyst such as platinum-supported catalyst or platinum alloy-supported catalyst (all claimed) for fuel cell electrode such as membrane electrode assembly (MEA) electrode.    ADVANTAGE - A high performance, high durability fuel cell catalyst can be provided. A crystalline carbon support that can be effectively used as a support of a fuel cell catalyst, can be provided, that is capable of creating an optimal electrode structure and that improves the support and dispersion of catalyst particles due to high oxidation resistance. A carbon support is provided having improved properties by crystallization of the carbon support and expansion of surface area. The materials are preferably heat-treated to improve the surface area and long-term stability. The crystalline carbon materials are pretreated to improve the crystallinity and increase the surface area, so as to improve the long-term stability and support performance, and to optimize the electrode structure. The concentration polarization, which is an important factor that affects the performance of the fuel cell, can be reduced. The performance improvement effect due to the optimized pore structure and the surface hydrophobicity and the performance improvement effect due to the improvement of the support performance interact with each other, in the case of the mixed support for the fuel cell. The performance of the electrode prepared using the mixed support has improved performance, particularly due to the activation of high potential and the improvement of material transfer at low potential region.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram showing a structure in which linear crystalline carbon nanofibers and acetylene black as fuel cell supports are mixed together.    Acetylene black (100)    Linear crystalline carbon nanofiber (200)