The invention relates to a method for preparing a multifunctional leaf fertilizer by using shrimp waste, which comprises the following steps: taking a large amount of fresh leftovers from the shrimp meat processing, hydrolyzing shrimp protein, cephaline, lecithin and chitin by using acid solution of a phosphor element needed by the leaf fertilizer; dissolving the calcium salt, magnesium salt, zinc salt, astaxanthin and the like in the shrimp shells by using alkaline solution of potassium element needed by the leaf fertilizer; and mixing the alkaline solution and the acid solution filtered out by the treatment of the two steps to obtain nutrient solution containing polypeptides, amino acids, phospholipids, chitosan, organic nitrogen, phosphor, potassium, calcium, magnesium, zinc, antifungal ingredients and the like, which can be absorbed and used by plants; and adjusting the pH value of the mixed solution rich in plant nutrients to 5 to 8 by using the alkaline solution of potassium or the acid solution of phosphor to obtain the multifunctional leaf fertilizer. The preparation method is simple in process, high in operability, high in added value, and environmentally-friendly and clean in production.