Antimicrobial peptides are the promising candidates for withstanding multidrug-resistant bacteria (MDRB) which were caused by the misuse and extensive use of antibiotics. In this research, in vitro activities of one antimicrobial cationic peptide, brevinin-2CE alone and in combination with five kinds of antibiotics were assessed against clinical isolates of extended-spectrum beta-lactamase-producing Escherichia coli and methicillin-resistant Staphylococcus aureus. The results showed that most of the combination groups had synergistic effects. Also, it was obvious that brevinin-2CE had more rapid and severe action on the tested MDRBs which demonstrated that brevinin-2CE and the antibiotics had different antimicrobial mechanisms. Thus, it was presumed that the antimicrobial peptides destroyed the bacterial cells via pore formation mechanisms which lead to the increasing of membrane permeability; and then the other compounds like antibiotics might enter into the cells and accomplish the antimicrobial activities more rapidly and efficiently.