The invention discloses a peach tree fertilizer and a preparation method thereof. The formula of the peach tree fertilizer consists of the following raw materials in parts by weight: 18-22 parts of dry chicken manure, 10-14 parts of dry duck manure, 11-15 parts of dry pig manure, 28-32 parts of dry rabbit dung, 28-32 parts of plant ash, 8-12 parts of bone meal, 4-8 parts of bean pulp, 8-12 parts of monopotassium phosphate, 8-12 parts of urea, 1-5 parts of auxin, 8-12 parts of trichlorfon, 18-22 parts of phenolic resin and 4-8 parts of fennel powder. The preparation method comprises the following steps: uniformly mixing the raw materials, and smashing to 50-60 meshes; adding liquid manure, mixing uniformly by stirring, and piling; and covering with plastic cloth for fermenting twice to obtain the peach tree fertilizer. The peach tree fertilizer is wide in the raw material source and low in cost. The formula and the preparation method of the peach tree fertilizer are simple. The prepared peach tree fertilizer is comprehensive in nutrition, and the defects of small peach tree leaf area, low growing speed, poor development, withering and falling of leaves, poor fruiting, small fruits and easiness in casing various pest and disease damages due to unreasonable match of a conventional fertilizer are overcome.