An integrated Cryogenian- Ediacaran sequence developed well in the Shennongjia area, northern margin of the Yangtze Craton, South China. Based on six Ediacaran sections bearing cap carbonates discovered recently in this area and a series of the sedimentary facies, this paper discussed the sedimentary environment of cap carbonates through systematically analyzing the stratigraphy, sedimentology and C- O isotope geochemistry. Cap carbonates in the western Shennongjia were composed of fine powder crystal dolomites have sharply contacts with the underlying tillites (and partly gradually transition), and have monotonous sedimentary structures which are mainly horizontal beddings or block stratifications. There are few other special sedimentary structures or lithological and mineral components, occasionally some cumular spharolite and leaf branchlike algae. The cap dolomites and overlying strata formed the rapid transgression sequence. The δ13 C values of the cap dolomites show a negative drift from extremely low (-6‰～-9‰) to medium low (-4‰～-5‰) in an ascending order, and a change from medium or low negative drift to much negative value, or a change around mediumlow negative values with high frequency oscillation, but δ13 C value of the overlying sediments remained medium- low negative. Sedimentary facies indicator and carbon isotopes study show that the cap carbonate rocks deposited in a shallow water shelf intertidal- supratidal flat, synchronously and diachronically with sea level rapidly rising. The 13 C value of the cap dolomite section at Shennongjia is basically similar to the change rule of the Ediacaran cap dolomite section in the world, with a wide range of global changes and correlation significance. Meanwhile, the 13 C value of the cap dolostone profile at Shennongjia is unique, which should be response to balancing the rapid rise of global sea level for the initial post- ice shallow water carbonate sedimentation. Further study found that the cap carbonates mainly developed in the shallow water shelf tidal in the central- west part of the Shennongjia area, but not in the deep- water basin, slope break and shelf.