Abstract: Objective To study the mechanism of cecropinA-mangainin treatment on the meticillin-resistant \Staphylococcus anreus biofilms. Methods The activity of the hybrid antibacterial peptide against \Staphylococcus anreus was evaluated by the minimum inhibitory concentration (MIC) test and its effect on the bacteria membrane changes were observed through transmission electron microscope. The concentration of K\+ of the tested bacterial liquid after interact with antibacterial peptide was detected with atomic absorption spectrometer. The changes of the treated bacteria biofilm was also evaluated by using flow cytometry. Results The results demonstrated that the MIC of the peptide against \Staphylococcus anreus was 64 μg/mL. The ultrastructure changes of the meticillin-resistant \Staphylococcus anreusmembrane and the rising concentration of intracellular K\+ were observed. And increased number of PI positive cells was also observed after hybrid antibacterial peptide treatmennt. Conclusion The hybrid antibacterial peptide could kill the meticillin-resistant \Staphylococcus anreusby damage the treated bacteria membrane.