The invention belongs to the technical field of agriculture animal husbandry and food antitoxin and detoxication, and relates to mycotoxin adsorbent and a preparation method thereof. The mycotoxin adsorbent is composed of, by weight, 85-90% of montmorillonite, 5-7% of yeast cell walls, 1-3% of chitin, 1-2% of saccharomyces boulardii and 3-5% of natural plant extract in a mixing mode. The natural plant extract comprises tea tree oil, hesperidin, eugenol, citral, cinnamaldehyde and baicalein which are proportionally mixed. The mycotoxin adsorbent can be applied to fodder, aflatoxin B1 in the mycotoxin can be absorbed, other mold toxins such as zearalenone, ochratoxin, deoxynivalenol and fumitremorgin can also be effectively absorbed, the nutrient absorption rate of the fodder is low, meanwhile, breeding and balancing of probiotics in intestinal canals can be promoted, and the immunocompetence of animals is enhanced.