Abstract: Objective: To establish a simple and rapid method for measuring the exogenous gene expression in eukaryotic cells.Methods: The plasmid that expresses green fluorescence,pOSM-EGFP-N1 was constructed by the insertion of the complete ORF of human oncostatin M （OSM） into pEGFP-N1 vector,and transfect Chinese hamster ovary（CHO） cells to get CHO-OSM-EGFP cells.After screening with G418 culture,the colony of expression green fluorescence was picked up under the fluorescence microscope.The CHO-OSM-EGFP cell line was obtained by continuously cultivation.Purity of cell line was checked by flow（cytometry）（FCM）.The OSM mRNA expression was examined by RT-PCR.Results: The CHO-OSM-EGFP cell line is stable expresses green fluorescence and the cell colonies with uniformly fluorescent intensity in culture and easily observed by fluorescence microscope.The purity of the CHO-OSM-EGFP cell line is 99.76% that analysis by FCM.The target gene OSM expression was detected in CHO-OSM-EGFP cell line by RT-PCR.Conclusion: These results showed that inserting the OSM gene into an expression green fluorescence vector,pEGFP-N1.The plasmid pOSM-EGFP-N1 transfect CHO cells,we can get stable expresses green fluorescence CHO-OSM-EGFP cell line.Through the green fluorescence expression,we will identify the exogenous gene expression in the eukaryotic cells.oncostatin M;fluorescence;gene expression;CHO cell