The cell localization analysis of 3- Phenoxybenzoic acid degrading-enzyme produced by Sphingomonas sp.SC-1 was studied in this article.The analysis showed that the degrading-enzyme was mainly located in the cell fragments.Separating the cell membrane fragments from concentration cell fragments by using sucrose density gradient centrifugation and detecting the effect on degrading 3-PBA.The result shows that the membrane fragments have some certain 3- phenoxybenzoic acid-degrading activity and it can be speculated that this enzyme is one kind of membrane protein on the cell membrane.Membrane protein with gel extraction separated from the sample by Native-PAGE was used to degrade 3- phenoxybenzoic acid.The band"c "had certain degrading activity.Using SDS-PAGE to analyze the band "c "and figure out that the molecular mass of degrading-enzyme is about 50 ~ 90 ku.