Middle to Lower Ordovician carbonate rocks are extensively distributed in the middle part of Central Uplift, Tarim Basin. As the dominant mineral of the carbonate rocks, the dolomite is analyzed in genesis. By observation of the rock cores and thin sections, six types of dolomites can be divided according to the different size, shape and euhedral texture of dolomitic crystals. Combined with the structural feature, the stable C and O isotope and Sr isotope analysis and the microscopic cathodoluminescence, it is considered that the Middle to Lower Ordovician dolomites formed in different diagenesis. Micritic and microcrystalline dolomites are formed by refluxion dolomitization during penecontemporaneous stage. Most of microcrystalline dolomites are formed by burial dolomitization during buried stage, in which a wide scale of dolomitization was during shallow buried stage. Coarse-crystalline saddle dolomites are formed by hydrothermal dolomitization during hydrothermal stage.