In order to clarify the controlling factors and formation mechanism of the high quality reservoirs in the Qigebulake formation, Upper Sinian, Tarim Basin, based on the data of five Sinian outcrops and two wells,this article has analyzed the reservoir petrology, reservoir porosities and infillings, rock stable isotope and trace elements through the methods of petrology and geochemistry. The results show that the Qigebulake reservoirsarech ara cterized by cavities, vugs and intergranular dissolution porosity development. The reservoir porosities are mainly developed in thrombolite dolostone, stromatolite dolostone and grain dolostone. On the analysisof reservoir controlling factors, it is determined thatthe presenthighquality reservoirs are modified by the diagenesis of penecontemporaneous dissolution, hypergene dissolution, hydrothermal dissolution,hydrothermal dolomitisation,organic acid dissolution, and fracturing, under the favorable sedimentary microfacies of microbial reef, microbial flat and grain-bank. The hypergene dissolution, hydrothermal dissolution and organic acid dissolution are the most significantfactors for the reservoirs, among which the hypergene dissolution is critical.