NOVELTY - Ocean biological calcium magnesium fertilizer is prepared by boiling fish bones with nitrogen and steam; drying fish, shrimp and crab aquaculture pond silt; soaking sea water spiral seaweed in water and low salt solution, and adding cellulase and pectinase mixed liquid; hydrolyzing e.g. internal organs and mixing with e.g. trypsin; carrying out enzymolysis with enzymolysis liquid; fermenting shell powder, crab powder, oyster shell powder, shrimp pool mud and ore powder with silicate bacterium; and mixing calcium amino acid polypeptide, Spirulina liquid, coral powder, and compost.    USE - Method for preparing ocean biological calcium magnesium fertilizer (claimed).    ADVANTAGE - The fertilizer enriches calcium, magnesium, zinc, silicon and multi-nutrient substance, and enhances easy absorption of nutrients.    DETAILED DESCRIPTION - Preparation of ocean biological calcium magnesium fertilizer comprises: (A) taking shell, crab shell, oyster shell and sea ore, drying, separately crushing into particle diameter of 1-1.5 cm to obtain powders; (B) cleaning fish bones in sonicator, ultrasonic crushing to less than 3 mu m, putting in high pressure kettle, adding 2-3 times water, introducing nitrogen to high pressure kettle at 0.9-1.7 MPa, processing for 11-29 minutes, filling steam into high pressure kettle at 1.7-2.9 MPa, boiling for 6-10 hours, removing oil, cooking for 30-40 minutes, and cooling to 45-55 degrees C to obtain bone soup; (C) taking fish, shrimp and crab aquaculture pond silt, drying to water content of 20-35%, and micro-crushing to 1-5 mm particle size; (D) microcrushing sea water spiral seaweed, soaking in distilled water for 10 days, soaking in low salt solution for 3-4 days, taking out, preparing cellulase and pectinase solution mixed liquid, controlling temperature at 32-42 degrees C, and high shear milling for 2-3 times to get Spirulina liquid; (E) taking trash fish or aquatic products, internal organs and mixed waste, cleaning, freezing and thawing for 3-5 times, mincing, adding soup obtained in second step, mixing, placing in microwave hydrolysis quartz cuvette, adjusting pH to 5.5-6.5, placing in hydrolysis tank, adding 110-130 ml 6 mol/L hydrochloric acid solution, covering pot, hydrolyzing, inserting temperature sensor, vacuumizing, filling with high purity nitrogen, repeating three times at 800 W, adding 0.5-1.5 wt.% trypsin, and heating to 40-60 degrees C for 2-3 hours to obtain calcium amino acid polypeptide; (F) cooling to room temperature, opening sealing device, pouring mixture into enzymolysis tank, adding 300-350 g/ton composite enzymolysis liquid, carrying out enzymolysis at 35 degrees C for 1-2 hours, stirring every 0.5 hour, oxygenating, and controlling pH at 3.5-6.2; (G) taking 10-20 pts. wt. shell powder, 10-20 pts. wt. crab powder, 10-20 pts. wt. oyster shell powder, 20-40 pts. wt. shrimp pool mud and 5-10 pts. wt. ore powder, mixing, taking 0.5-1.5 pts. wt. 10-100 hundred million/g silicate bacterium, diluting up to 2-5 times, spraying raw material, mixing uniformly, spraying brine to raw material, mixing uniformly, fermenting for 10-20 days, stacking and fermenting for 5-10 days, drying to water content of 6-10%, and crushing into 20-100 meshes fine powders to obtain mixed fertilizer; and (H) taking 3-10 pts. wt. calcium amino acid polypeptide, 3-10 pts. wt. Spirulina liquid, 3-10 pts. wt. coral powder, and compost obtained in seventh step, mixing, granulating and drying to moisture content of 12-24%.