The invention discloses a special fertilizer for a tuberiferous plant, and a preparation method thereof, belonging to the field of agricultural technology. The fertilizer is prepared from comprising the following raw materials: 25% of peanut straws, 30% of garlic straws, 25% of animal excrements, 11% of bean pulp, and 9% of traditional Chinese medicine component, wherein the traditional Chinese medicine component comprises the following active ingredients in parts by weight: 4 parts of fructus quisqualis, 5 parts of cortex meliae, 8 parts of indian quassia, 2 parts of semen arecae, 2 parts of cushaw seed, 2 parts of gemma agrimoniae, 2 parts of omphalia, 2 parts of fructus carpesii, 2 parts of semen torreyae, 2 parts of fructus ulmi, 4 parts of pyrethrum cinerariifolium, 3 parts of iris tectorum maxim, 3 parts of garlic, 4 parts of cacumen platycladi, and sunflowers; the preparation method comprises the steps of traditional Chinese medicine soaking, fermentation, drying, smashing, and packaging. The fertilizer has the insecticide function while having the fertilizer function by adding the traditional Chinese medicine components of insecticide, thus greatly reducing the diseases of crops; in addition, the garlic straws also contain abundant allicin and the like, thus having the bacterial and pesticidal roles, and achieving the synergistic effect on the traditional Chinese medicine components.