Abstract: Hydrothermal activity played an important part in the formation of dolostone reservoirs in Tadong area (eastern Tarim basin). By applying the technologies of rock thin section microscopic identification, cathodoluminescence analysis, carbon and oxygen isotope analysis, trace element, rare earth element analysis, etc, the hydrothermal process and formed Cambrian hydrothermal dolostone reservoirs in Tadong area were studied. There are two stages of hydrothermal processes with transformed effect significance on the Cambrian carbonate reservoirs, and corresponding rock mineralogical and geochemical identification marks of the two hydrothermal processes are established. The Stage?Ⅰhydrothermal process took place in the Middle-Late Ordovician, its transformed effect on the Early Cambrian consolidateddolomites was dominated by formation of fractures rather than on the Cambrian microcrystalline limestone, marl and mudstone intervals. The Stage?Ⅱ hydrothermal process took place in late hercynian at the end of Permian, and its transformed effect created wide distribution of hydrothermal dissolution and formed Cambrian important dissolution fractured?vuggy reservoirs in this area