The invention discloses a preparation method of metal icosahedral nanoparticles. The preparation method is as follows: at room temperature, adding polyvinylpyrrolidone into noble metal precursor aqueous solution; stirring uniformly, then adding ammonia water, and stirring for 10-30 minutes at room temperature; transferring the prepared reaction solution into a reactor, sealing and reacting for 2-10 hours at the temperature of 100-200 DEG C; after cooling, centrifuging products, collecting precipitates, and cleaning for 2-3 times by deionized water and absolute ethyl alcohol to obtain the metal icosahedral nanoparticles. Compared with the prior art, in the invention, the polyvinylpyrrolidone is used as both a surface active agent and a reducing agent, the preparation cost is obviously reduced, and water which is low in cost and easy to obtain is used as a solvent and a reaction medium, thus the synthetic method is simple and environment-friendly, is finished by one step, is easy to operate and has strong reproducibility; and the prepared product has the characteristics of high yield, high purity, uniform size distribution and the like, has excellent catalytic activity and can be used for heterogeneous organic reaction catalysis, electric catalysis, electrode materials of fuel batteries and the like.