In this paper, the influence to bacterial surface characteristics and interaction mode with liposomes of antimicrobial peptides BF2-A and BF2-B, two analogues of Buforin Ⅱ, had been researched. The both peptides could enhance the electronegativity and hydrophobicity of cell surface of Gram-positive bacteria and Gram-negative bacteria, which determined by Zeta potential electrometer and hexadecane extraction, respectively. BF2-A/B could cause calcein release from large unilamellar liposomes consisted of the anionic lipid phosphatidylglycerol and the zwitteronic lipid phosphatidylcholine, which reflected the compositions of bacterial cytoplasmic membrane. BF2-A displayed much weaker leakage than that of BF2-B, suggesting that BF2-B might cause perturbation of the phospholipid bilayer of the plasma membrane. However, BF2-A/B didn’t collapse the membrane of liposomes. Then the peptides were labeled with FITC. The blue shift of fluorescence spectra and the augmentation of quantum yield of FITC-peptides were discovered after the addition of liposomes. And the fluorescence quenching of FITC-peptides by acrylamide was prevented under the protection of liposomes, which implied that the N-terminal of BF2-A/B inserted into the phospholipid bilayer of membrane.