CAMA-syn, a hybrid composed of N-terminal α-helical segment of Cecropin A(amino acid 1-8) and Magainin 2 (amino acid 1-12), is a novel small peptide with the potent antibacterial and synergistic activity without cytotoxicity. In order to test the antibacterial function of CAMA-syn produced in mammalian cells, several vectors containing the synthesized CAMA-syn DNA fragment were constructed and transfected into recipient cells. The results showed that CAMAsyn fusion to green fluorescent protein (GFP) or to hemagglutinin epitope (HA) tag was expressed in both bovine embryo fibroblasts (BEF) and mouse macrophage RAW264.7 cells. The antibacterial assays of CAMA-syn were conducted against both Gram positive and negative bacteria, including S. abortusovis, P. anatis, S. hyicus and S. suis. The results of colony-forming efficiency and cell growth curves proved that the in vitro expressed CAMA-syn could have the antibacterial activity, demonstrating that macrophage specific expression of antimicrobial peptide CAMA-syn could inhibit the growth of bacteria.