The invention discloses a sterilizing organic-inorganic spherical special fertilizer for aquaculture. The special fertilizer overcomes the problems of a single function, incapacity of meeting growth and development demands of fish and the like of conventional fertilizers. The special fertilizer is characterized in that the special fertilizer is prepared from organic fertilizer, inorganic fertilizer, zeolite powder, trace element amino acid chelate, compound sodium nitrophenolate, em probiotics, etc. through mixing and granulation. A preparation method for the special fertilizer comprises the following steps: uniformly mixing the organic fertilizer with other raw materials; then conveying the obtained mixture to a granulator for granulation; delivering the granulated material to a dryer for drying, wherein heat of the dryer is supplied by combustion of coal; subjecting the dried material to cooling and screening; and packaging the obtained finished product with a particle size of 1.5 to 3 mm and warehousing the product. The special fertilizer is applicable to culture of grass carp, crucian carp, carp, silver carp, bighead carp, catfish, tilapia, colossoma brachypomum, saltwater fish, soft-shelled turtle, mandarin fish, eel, river crab, prawn, white prawn, freshwater shrimp, Ma shrimp, macrobrachium, lobster, loach, swamp eel, sea cucumber, abalone, pearl, mussel, Sinonovacula constricta, oyster, green lipped mussel, clam, Tegillarca granosa, shellfish, laver, sea-tangle, etc.