The invention relates to the field of agricultural fertilizers, in particular to a compound fertilizer for preventing and treating dead vegetables and a preparation method thereof. Mix 500,000 parts of sodium humate, 100,000 parts of urea, 200,000 parts of avermectin powder, and 100,000 parts of lemon pomace in a weight ratio, grind them to more than 80 meshes, enter the stirring tank, and adjust the pH value to 7.6; add 1,000,000 parts of fertilizer during the stirring process 2000 parts of Bacillus licheniformis, 2000 parts of Bacillus subtilis, 1000 parts of sodium naphthalene acetate, 800 parts of gertyl milk powder, 200 parts of gibberellic acid, 1000 parts of iron powder, 1000 parts of zinc powder, 1000 parts of copper powder, 1000 parts of boron powder, 20 parts of N-(2-benzoimidazolyl)-methyl carbamate, 15 parts of 3-hydroxy-5-methylisoxazole, 10 parts of tolclofos-methyl, ethanethiosulfonate 20 parts of ethyl acetate. The effect is obvious, and the problem of dead vegetables can be effectively prevented and treated.