Abstract: The dolomite of Upper Sinian Qigebulake Formation in Tarim Basin is deeply buried and rarely exposed by drilling, and is less explored and studied. Through dense sampling (1.28 sample/m) on the Sinian outcrop profile in Keping area, Tarim Basin, the lithology, physical property and genetic mechanism of dolomite in Qigebulake Formation are systematically investigated. It is clarified that Qigebulake Formation has five major reservoir types, i.e., sparry-spongiostromata dolomite, karst-breccia domomite, residual-grain dolomite, fine crystalline dolomite and calcite dolomite. The vertical and lateral distribution regularity of reservoirs is confirmed as below: three reservoirs are mainly developed vertically with the total thickness of 65.7~95.9 m, the porosity of 5.1 % ~5.3 % and the reservoir-layer thickness ratio of 0.42~0.53. The distribution of top reservoirs in the Qigebulake Formation is relatively stable, while the mid-bottom reservoirs are distributed discontinuously from Keping to Tabei area. Sedimentary facies, weathering-crust karstification and hydrothermal dissolution are the main controlling factors for forming high-quality reservoirs. Fractures play a constructive role in the improvement of physical properties. The high-quality source-reservoir-cap assemblage consists of Sinian dolomite and the overlapping black shale in Yuertusi Formation, which is a new ultra-deep exploration field, and Tabei area is a realistic exploration area in this field.