Abstract: Sr isotopes of limestones for the Precambrian-Cambrian boundary from the Xiaotan section, Yongshan, Yunnan province, and Sr and C is otope s of carbonates for the Sinian System from the Sanxia section, Hubei province have been investigated. The results were compared with the Sr and C isotopic data der ived from Mongolia, Canada, Siberia and Namibia. A variation curve of　8 7Sr/86Sr and δ13C for the seawater of the terminal Proterozo ic was pr oposed. 　　Just before the terminal Proterozoic, the δ13C value of seawater was high , about +11‰, and the　87Sr/86Sr was about 0.7072. At the period o f glaciation corresponding to the Nantuo/Ice Brook, the δ13C value of sea water was negative, about -5‰, and the　87Sr/86Sr was about 0.7 077. Later on, the δ13C value rapidly rose with at least three fluctuations. At the time corresponding to the Dengying formation, the δ13C value showed a flat terrace about +2～+3‰, and the　87Sr/86Sr about 0.7084. At t he Precambrian-Cambrian boundary, the δ13C value rapidly rose from a neg ative value to about +6‰, and the　87Sr/86Sr kept at about 0.7084 . 　　From the variation curve of　87Sr/86Sr and δ13C for seawater proposed in the present study, the strata of the terminal Proterozoic in the world can be correlated with each other.