The invention discloses a method for preparing a carbon-supported high-activity gold or gold-platinum alloy or gold-core platinum-shell structural nano catalyst. The supporter of the catalyst is carbon black, and the active ingredient is gold or gold-platinum alloy or gold-core platinum-shell structural nano particles. The method is characterized by comprising the following steps of: modifying porous carbon by using a self-assembly method and using phi-phi bonds of a modifying chemical reagent to obtain a mercapto functionalized carbon black supporter, and depositing the gold or gold-platinum alloy or gold-core platinum-shell structural nano particles on the surface of the mercapto functionalized carbon black to obtain the gold or gold-platinum alloy or gold-core platinum-shell structural nano carbon-supported catalyst with high activity. The catalyst obtained by the method has high gold load factor; the load of the gold is controllable; the gold-carbon catalyst containing 1 to 64 mass percent of gold can be prepared; the catalyst has high activity, the size distribution of the gold nano particles is uniform and can be controlled, and the gold nano particles are connected with the porous carbon through the chemical bonds containing conductive benzene rings so as to enhance the interaction of the gold nano particles and the carbon; and the method has the advantages of low cost, simple process and low equipment requirement, and has good industrial application prospect.