The main immunogenic protein of the porcine epidemic diarrhea virus (PEDV) is the spike protein (S protein), which plays an important role in receptor binding, membrane fusion, and viral invasion of the host. In this paper, the linear epitope of the 3F10 non-neutralizing monoclonal antibody that was previously prepared in our laboratory was identified. The expression of truncated forms of the S protein for 3F10 reaction studies proved that the epitope was located between amino acids (aa) 674 and 791. To further locate the core aa of the 3F10 epitope, 12 random peptide libraries were used, and the result showed that the key aa located at aa 685-688 of the S protein (LLAF) were recognized by 3F10. Homology analysis of the regions corresponding to 20 typical strains of different PEDV subtypes showed that the epitope is highly conserved. Identifying the epitope recognized by an antibody helps to improve our understanding of the structure and function of the antigen. Keywords: spike protein; linear epitope; homology analysis.