According to the partiality codon of Pichia pastoris, hybrid antimicrobial peptide CecA-mag gene was synthesized and cloned into pPICZa-A to construct the recombinant expression vector pPICZa-A-CA. The SacI-linearized plasmid pPICZalpha-A-CA was transformed into P. pastoris SMD1168 by electroporation. Under the control of the promoter AOX'(alcoholoxidase') , an approximately 1.9kDa cecA-mag protein was expressed. Antibacterial assays demonstrated that cecA-mag had broad spectrum of antimicrobial property against Gram-positive as well as Gram-negative bacteria especially showed potent antibacterial activity against ampicillin resistant bacteria, such as pathogenic E. coli. In addition, the hybrid antibacterial peptide showed an extreme heat stable and acid stable characteristic. These results suggest that the P. pastoris expression system can be used to produce large quantities of fully functional cecA-mag for both research and industrial purpose. Based on these characteristics, the recombinant antibacterial peptide cecA-mag displays application foreground in the field of prevention of disease, and can be used as additives of animal feedstuff and so on.