The invention discloses a prussian blue derivative Fe-Co-Ni sulfide and preparation method and application thereof. The prussian blue derivative Fe-Co-Ni sulfide is of a three-dimensional porous structure and is obtained by vulcanizing Fe-Co-Ni prussian blue, the frame is fixed by carbon, and the prussian blue derivative Fe-Co-Ni sulfide is prepared by a wet chemical method and by subsequent vulcanization and thermal processing. The prussian blue derivative Fe-Co-Ni sulfide has ultrahigh specific capacity, favorable cycle property and excellent rate performance when used as a sodium/potassiumion battery negative electrode. Compared with other sodium/potassium ion battery negative electrode materials, the material has the advantages that the mass specific capacity of the negative electrodematerial can be effectively improved, and the energy density of all batteries is improved; and meanwhile, the preparation method is simple and practical, and industrial production of the sodium/potassium ion battery negative electrode material is expected to be achieved by corresponding development.