The invention provides a preparation method of a special organic fertilizer for navel oranges. The prepration method comprises the following steps: step one, after mixing 150 to 200 parts of a seafoodshell powder, 50 to 80 parts of rice bran and 100 to 200 parts of a seaweed hydrolysate uniformly in parts by weight, and standing for 2 to 3 hours; step two, adding 1 to 20 parts of molasses, 1 to 20 parts of urea, 1 to 5 parts of plant ash, 1 to 5 parts of a sea-foam stone powder, 1 to 20 parts of monopotassium phosphate, 1 to 5 parts of zinc sulfate, 1 to 5 parts of boric acid, 1 to 5 parts ofmagnesium sulfate, 1 to 5 parts of ferrous sulfate, 0.5 to 2 parts of manganous nitrate, 0.5 to 2 parts of copper sulfate and 0.1 to 1 part of sodium molybdate in parts by weight, and after uniform mixing, carrying out chelation at the temperature of 60 to 70 DEG C for 24 to 36 hours so as to obtain the special organic fertilizer for navel oranges. The invention provides a preparation method of the special organic fertilizer for navel oranges.