The invention discloses a technological method for preparation of sphere-shaped ultrafine metallic powders through hydro-thermal treatment, which relates to a technological method for preparation of sphere-shaped ultrafine nickel powders or ultrafine cobalt powders through the procedures such as precipitation, dispersing agent surface finish, high-pressure hydro-thermal treatment, washing, drying and high-temperature hydrogen reduction and the like, and which belongs to the technical field for preparation of metal powder materials. The technological method adopts water soluble salts with nickel and cobalt, cobalt oxide, sub-carbonate, carbonate or hydroxide as raw materials, which are prepared into water solution after processing, the dispersing agent is added, then nickel ion and cobalt ion in the water solution are precipitated through alkali, carbonate, oxalic acid or ammonium oxalate and the like, the hydro-thermal treatment of water pulp of the precipitate is performed in an autoclave, and products of sphere-shaped ultrafine nickel powders or ultrafine cobalt powders with even graininess and good dispersibility can be obtained through washing, drying and high-temperature hydrogen reduction. The technological method is not only suitable for medium- and small-scale discontinuous-type manufacture, but also used for large-scale continuous manufacture, and the manufacturing cost is low.