Functional materials in microorganism cell,cell membrane and cell wall could be dissolved by supercritical carbon dioxide.As a result,the microorganism cells would be damaged and may die because of inactivation.The extraction mechanism of supercritical carbon dioxide in sterilization was studied in this paper.The E.coli suspension was treated by supercritical extraction at same conditions and the composition of different extraction liquid samples after different time was analyzed.The results showed that there were two species of extract:nonpolar fatty acid material and polar weaks small member amino acid material,hich were both functional materials of cell.In this way,extraction was indeed happened in sterilization by supercritical process.