Previous studies have demonstrated that chemically synthesized peptides from the hemocyanin of the shrimp possess antibacterial activities. However, to date, little is known about their immune regulatory function. In this study, a chemically synthesized peptide, B1, from the hemocyanin of shrimp was investigated using proteomics, molecular biology, and immunological strategies. The results showed that, compared with the control, two protein bands with sizes 65 kD and 35 kD (designated as p65 and p35, respectively) were significantly upregulated in shrimp plasma following stimulation with peptide B1. LC-MS/MS and Western blot analyses revealed that p35 and p65 shared a high degree of homology with 13 proteins, including hemocyanin, -1,3-glucan-binding protein, and transglutaminase. Moreover, p65 could bind specifically to rabbit anti-shrimp hemocyanin antibody. Quantitative real-time PCR analysis demonstrated that five LC-MS/MS-identified genes, including hemocyanin large subunit, hemocyanin small subunit, transglutaminase, α2 macroglobulin, and glucan pattern-recognition lipoprotein, were significantly (<0.01) upregulated in shrimp hepatopancreas, gills, and hemocytes following stimulation with peptide B1. Collectively, our data demonstrated that peptide B1, chemically synthesized from hemocyanin of the shrimp , may possess regulatory properties and induce the expression of different immunological factors including hemocyanin.