The invention relates to a preparation method and application of an immune preparation capable of enhancing immunities of fishes, prawns and crabs, and belongs to the technical field of nutrition immunology. By feeding an immuno-potentiator containing such nutrients as nitric oxide, amino acid, beta-brown shell color, anthocyanin, vitamins and trace elements, oxygen radicals and viruses in the fishes, prawns and crabs are removed or inhibited; moreover, the immune preparation can regulate metabolism of bred animals, and has a certain growth promoting effect; the immune preparation is favorable for reducing a death rate and improving breed output of the bred animals.