The invention discloses a bovine viral diarrhea virus (BVDV) E2 multi-epitope fusion peptide and a preparation method thereof. The preparation method comprises the following steps: performing gene synthesis on two respective epitope tandem sequences of optimized E2 proteins such as BVDV-1 and BVDV-2, cloning the sequences to a pET-28a (+) vector, transforming Escherichia coli DH-5alpha, transforming Escherichia coli BL21 from an accurate recombinant vector, performing IPTG inducible expression, and performing Ni-NTA purification, so as to obtain the BVDV E2 multi-epitope fusion peptide. Afterbeing subjected to animal immunization, the E2 multi-epitope fusion peptide is capable of producing a neutralizing antibody of the BVDV, and can be used for research and development of BVDV epitope vaccines; an ELISA (Enzyme-linked Immuno Sorbent Assay) detection kit prepared by utilizing the E2 multi-epitope fusion peptide can be used for BVDV antibody detection of cattle, and has the advantagesof being high in specificity, high in sensitivity, excellent in repeatability and easy to operate.