Carbon isotope of loess through S0 to S 11 at luochuan section in Shaanxi Province were experimented.The curve of δ 13C compares well to the oxygen isotope curves of deep sea sediments from DSDP607 drill.There is obviously negative peak of δ 13C within S5 paleosol where the content of δ 13C is-16.615‰,that shows the climatic optimum,and the vegetation during the period is likely forest.Comparing with the pollen analysis,the vegetation type of paleosol S0,S1,S4,S8,S9 which δ 13C content is-5.85‰～-10.00‰,is forest-grass.δ 13C content of paleosol S2、S3、S6、S7 is-8.72‰～-6.95‰,their vegetation is grass.The loess layer L1、L2、L5、L6、L8、L9 represent the severe cold-dry glacial period with δ 13C content of-3.7‰～-2.27‰,their vegetation belonging to steppe-desert.
