The invention belongs to the biological technical field, and in particular relates to preparation and application of a zearalenone anti-idiotype nano antibody, which has an amino acid sequence SEQ ID No.1, also relates to the nucleotides encoding the amino acid. The nano antibody of the invention can replace the expensive toxic Zen standard, and can be used in immunological detection of Zen as a competitive antigen or solid coating antigen. the nano antibody has similar immunological properties to natural Zen molecule, and good effect. Compared to a traditional antigen mimicking epitope based on polypeptide and a traditional anti-idiotype antibody based on IgG, the nano antibody has the advantages of more stable structure, acid resistance, alkali resistance, high temperature resistance and high detection sensitivity, so that the immune detection stability has been greatly improved, and the tolerance on the environment has also been improved.