Abstract: Abstract：The Cambrian-Ordovician dolomite in Tarim basin is characterized by old age, deep burial and complex diagenesis. The space of the dolomite reservoir is mainly composed of pores and cracks. The pores can be further divided into such types as intercrystal pores, intercrystal dissolved pores, intracrystal pores, moldic pores and dissolved holes, while the cracks can be further divided into satures, weathering fractures and structural fractures. According to the characteristics of reservoir space, dolomite reservoirs can be divided into four kinds, i.e., pores, vuggies, fracture-pores and fractures, in which pore and fracture reservoirs are better than others. Based on the origin, dolomite reservoirs can be divided into three types, namely syngenesis, burial, structure-hydrothermal solution and weathering-crust corrosion, among which the last two types and their combinations often formed high quality reservoirs.