The invention discloses a preparation method of an organic-inorganic compound fertilizer for high-quality black salted turnip. The organic-inorganic compound fertilizer for the high-quality black salted turnip is prepared from the following raw materials in percentage by total weight of the organic-inorganic compound fertilizer: 28%-35% of urea, 12%-16% of ammonium phosphate, 16%-18% of potassium sulfate, 2%-5% of magnesium sulfate, 1%-2% of ammonium molybdate, 1%-2% of boric acid, 0.5% of zinc sulfate, 11%-15% of rapeseed dregs, 7%-11% of chicken manure, 9.5%-12% of soybean meal and 5%-7% of granulating regulating agent. The organic-inorganic compound fertilizer for the black salted turnip contains multiple major elements and trace nutritive elements which are necessary for plants, wherein the total nutrient content of nitrogen, phosphor and potassium is greater than or equal to 30%, and the content of organic matters is greater than or equal to 15%. The organic-inorganic compound fertilizer is rich in multiple elements such as nitrogen, phosphor, potassium, magnesium, boron and molybdenum which are necessary for growth of the black salted turnip, so that the growth, development, high-quality and high-yield requirements of the black salted turnip are satisfied; meanwhile, the soil structure is effectively improved, and the utilization rate of the fertilizer is greatly increased.