A preparation method of a fertilizer special for asparagus lettuce comprises the following steps: raw materials metering, mixing, raw material melting, liquid material slurry filtration, slurry spraying, cooling and granulation, granule screening, and finished product packaging, the fertilizer comprises the following components and raw materials: 16-17 parts of urea, 4-5 parts of monoammonium phosphate, 18-20 parts of potassium chloride, 3-4 parts of calcium oxide, 2-3 parts of zinc sulfate, 1-2 parts of boron fertilizer and 2-3 parts of sodium nitrophenolate. The melted and granulated special fertilizer is uniform in release of fertilizer efficiency, is relatively long in effect time, is not easy to scatter during storage and transportation and use processes, and is less in loss, by applying the fertilizer, asparagus lettuce plants are vigorous in growth vigour, the plant height is 60cm, the stem diameter is 8cm, the yield is high, the rough weight per plant is 2kg, the net weight per plant is 1.6 kg, the net vegetable rate can reach 80%, the product is green in leaf and stem, not easy to bolt, good in commercial appearance, high in seal price, easy to sale, and capable of achieving better economic benefit.