The invention provides a method for preparing a high-dispersion and high-specific-surface-area transition metal alloy catalyst by using the migration between solid phases and belongs to the field of green energy source materials. According to the method provided by the invention, a transition metal salt, and micro-molecular substances capable of being used as a reactant, a dispersant and a blocking agent are ground and uniformly mixed, and then a mixture is transferred into a reaction container; one layer of solid reducing agent is flatly paved on the surface and is kept for a period of time at a room temperature; a product is centrifuged, washed and dried to obtain the transition metal alloy catalyst. An experiment shows that a transition metal alloy prepared by the invention also has relatively high dispersity, high specific surface area and high activity, and can be applied to a plurality of fields of catalyzing ammonia borane, hydrolyzing sodium borohydride type compounds to produce hydrogen, catalyzing methanol oxidation and the like; furthermore, the method is simple in process and low in cost and any solvent and any auxiliary agent are not needed so that the method is environmentally friendly; the product has controllable particle size and reaction speed, so that the method has a very good industrial application prospect.