The invention relates to a preparing method and application of ecological matrix particles for river water body enhanced nitrogen removal. The problems that C/N of a river water body is low, a carbon source capable of being used by microorganisms is insufficient, the denitrification effect is inhibited, and the TN removal rate is small can be effectively solved. Corncob powder is smashed, added into a sodium hydroxide solution to be soaked, dried, irradiated by ultraviolet light to obtain modified corncob; a high-permeability porous inorganic material, an inorganic binder and the modified corncob are stirred to be mixed uniformly and pelleted; the prepared spherical particles are laid on a flat plate, placed in a shady and cool place, cured, and sprayed with water in the morning and evening every day until particle surfaces are moist, curing is completed, and the ecological matrix particles can be obtained through airing. The ecological matrix particles can be used as matrix filler in riverway in-situ/heterotopias recovery technology of an ecological floating bed, an ecological filtering dam, an ecological percolation island, an ecological revetment, a constructed wetland, an ecological filter tank, an ecological filter bed and the like. The ecological matrix particles are rich in raw material, easy to produce and prepare, low in cost, good in use effect, long in service life, huge in economic and social benefit.