Abstract:Antibacterial peptide is a kind of immune effect factor, it plays an important role in innate immune system of biological organism. It has many kinds of biological activity, like broad spectrum of antibacterial, resisting parasites, antivirus, antitumor, antioxidation and so on, especially its high toxicity to some kinds of cancer cells and low toxicity to normal cells cause the researchers’ attention. Cipangopaludina cathayensis is used as the research object, this study extracts antibacterial peptide preliminary from Cipangopaludina cathayensis and determines its antibacterial effects, physical and chemical properties and tumor-suppressor activity. The results show that: the bacteriostatic effect of the crude extraction is obvious; with the treating temperature increasing, treatment time extending, antimicrobial activity reduce gradually, but still show good thermal stability; Under the weak acidity (pH 4~6)conditions, antibacterial activity tended to increase as the acidity reduces. Under the neutral and alkaline (pH 7~12) conditions, antibacterial activity reduces as the alkalinity increases; With freezing and thawing times increasing, antibacterial activity changes slightly; crude extraction shows inhibition to A549 cells’ proliferation .