The invention relates to the field of composite fertilizers, in particular to a slow-release composite fertilizer capable of preventing crop premature senility and pest and disease damage. The fertilizer is prepared from the following raw materials in parts by weight: 10-15 parts of 1,250-2,000-mesh diatomite, 20-22 parts of diammonium phosphate, 10-12 parts of calcium magnesium phosphate fertilizer, 6-8 parts of borax, 10-12 parts of leftovers in a grape wine plant, 2-3 parts of litsea cubeba leaves, 12-15 parts of germinated brown rice, 12-15 parts of potassium magnesium sulfate, 2-4 parts of ferrous sulfate, 15-18 parts of fermented manure, 4-6 parts of potassium silicate, 1-3 parts of bacillus megatherium, 10-12 parts of yellow bean residues, 13-14 parts of waste mushroom culture materials, 1-3 parts of marigold root water extract, 0.1-0.2 part of artemisia vulgaris oil, 12-15 parts of gelatin, 2-3 parts of animal grease, 1-2 parts of Tween 80, 3-5 parts of magnesium stearate and 4-5 parts of an assistant. The composite fertilizer is rich in raw material type and rich in nutrition; nutrients are double coated with the diatomite and a slow-release coating agent, so that the fertilizer efficiency is relatively lasting; moreover, the composite fertilizer has environment-friendly and safe pest-proof, corrosion-proof and bactericidal effects, so that the soil activity is good, the crop premature senility is hardly caused, the crop yield can be effectively increased, and the crop quality can be effectively improved.