The oral cavity sterilizing and cleaning liquid is prepared through mixing chitin, fucoxanthin, spirulina and balloonflower root and mint leaf extractive as effective sterilizing components and pure water. It is one kind of green biological product and has the features of high sterilizing and deodorizing efficiency, low concentration, high stability, scented smell, no toxicity, no irritation andno corrosion. It is used in sterilizing and cleaning oral cavity, especially eliminating bad smell of oral cavity. The technological process of preparing the oral cavity sterilizing and cleaning liquid is also provided.