Disclosed is a method for preparing powder carrying nano gold by thermal decomposition, comprising the steps of: (1) providing a nano powder of artificial synthesized material or a natural mineral powder which particle size is in nano to micro scale as a carrier, preparing 0.2-5.0% (weight percentage concentration) gold bromide solution with deionized water and gold bromide, adding the carrier into the gold bromide solution, and a weight ratio of gold bromide and carrier is 1:1-1:1000, immersing the carrier into the solution for 0.5-4 hours in dark; (2) drying the immersed carrier and the solution at 50-90.degree. C., and grinding the carrier to the fine mixed powders; and (3) heating the mixed powders obtained in step (2) at 200-350.degree. C. for 0.5-3 hours in a heating apparatus flown argon gas or air at a flow rate of 1-10 L/min, and obtaining the carrier powder carrying nano gold after decreasing the heating temperature to room temperature under continuous air flow. The advantages of present invention includes: (1) it is a simple process, low cost, (2) there are no dispersant agent and surfactant in the product, and (3) there are no poisonous or harmful materials are excluded in the preparation process.