Helicobacter pylori is a major cause of chronic gastritis, peptic ulcer disease, and associated with gastric carcinoma. H. pylori Neutrophil-activating protein (HP-NAP) is one of the major virulence factors. It has been shown that HP-NAP is a good candidate antigen for a multi-epitopes vaccine against H. pylori. However, the B-cell epitopes of HP-NAP are largely unknown. Bioinformatic and immunological approaches are used to map B-cell epitopes of this antigen. Four high antigenic peptides located in different regions were found by B cell epitope prediction. Three mAbs were produced by using recombinant HP-NAP-GST as the immunogen by the standard hybridoma technique. The immunohistochemical staining showed that mAbs against HP-NAP specifically reacted with clinical strains of H. pylori. Three different mimicry B-cell epitopes as mimotopes of HP-NAP protein are identified through screening the phage displayed peptide libraries with these mAbs.