Abstract: Objective:To determine the content of total polyphenols in aboveground part and underground part of Sedum aizoon L. , and to research the antimicrobial activities of the 70% methanol extract from Sedum aizoon L. Methods:The content of total polyphenols was determined by Folin-Ciocalteu colorimetric assay with gallic acid as reference. Heat reflux extraction was used to get 70% methanol extract, and antimicrobial activity was evaluated using the Oxford cup method and 96-well plates to measure the size of the zone of inhibition, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) . Results:The results showed that the contents of total polyphenols in aboveground part and underground part of Sedum aizoon L. were (45. 59±0. 87) mg/g and (96. 25±0. 47) mg/g, respectively. And the 70% methanol extract from Sedum aizoon L. was active against almost all tested microbial species. The Staphylococcus aureus was most inhibited by the methanol extract, the MIC and MBC was 6. 25 and 25mg/mL, respectively.