The invention relates to an all-nutritional compound type liquid fertilizer for being sprayed to plant leaf surfaces and a preparation method thereof. The fertilizer contains major elements, secondary elements, trace elements such as chelate iron, zinc, manganese, copper, molybdenum, boron and chlorine which are necessary to the growth of plants, biological hydrolytic amino acid and a plant growth regulator, wherein the total amount of nitrogen, phosphorus and potassium elements contained in 16 elements which are necessary to the growth of the plants is more than 110 grams / liter; the total amount of calcium, magnesium and sulphur elements contained in 16 elements is more than 30 grams / liter; the total amount of the zinc, the manganese, the iron, the copper, the boron, the molybdenum and the chlorine contained in 16 elements is more than 50 grams / liter; the amount of the amino acid in the fertilizer is more than 100 grams / liter; and the amount of the plant growth regulator in the fertilizer is more than 20 grams / liter. The fertilizer is a non-toxic, pollution-free and environment-friendly fertilizer; by spraying the fertilizer to the leaf surfaces, the nutrition of crops can be replenished comprehensively, physiological diseases are prevented and controlled, the expansion and elongation of plant cells can be promoted, the formation of chlorophyll is induced, flower and fruit retention are realized, and the yield of crops is improved.