Abstract: The Tertiary are saline sediment in western part of Qaidam Basin. The source rocks of oil contain much of carbonate and some strata even contain halite and mirabilite. The concentration of chlorine is higher in rocks. The composition and distribution of biomarkers have a close relationship with their sedimentary environment. The increasing of salinity in sedimentry environment can restrain the transformation from Tm to Ts. In addition,the formation of Ts may relative to some aquatic organism in saline facies. Sterane parameter of C₂₇/C₂₈十C₂₉ ratios which can reperesent the input information of organism have a positive relationship with the concentration of Cl^一Show that because of dry climate, the supplying of higher plants decrence,the salinity incrence in water and some aquatic organism which can living in saline water may incrence. Many publications have shown that the hopane parameter of C₃₁S/R ratio and the sterane parameter of C₂₉ββ/aa十ββ ratio both can reflect the maturity degree of source rocks and oils. But in Qaidam Basin,when the concentrations of carbonate is lower than 25%,both of the C₃₁S/R ration and the C₂₉ββ/aa十ββ ration have a pesitive relationship with the concentrations of carbonate,when the concentrations of carbonate is higher than 25%,both of the parameters have a negative relationship with the concentrations of carbonate. Show that the higher amount of carbonate have a restricted effection on the isomerisation of sterane and hopane.