Recently, dolomiticrock exploration of Junggar Basin has made a sustained breakthrough and opened a completely new exploration field. Definition of dolomiticrock is concluded, and the effective reservoir type, characteristics of occurrence and formation mechanism of dolomite are determined based on previous research conclusions, core observation, thin section, and so on. The dolomiticrock with special lithology and limited distribution mainly develops in Permian Fengcheng Formation of Wuxia district of the northwest margin. The dolomite has seven types of occurrence,including lameltate, uniform distribution, snow shape, irregular layered shape, crumb shape, fracture filling shape and exotic dolomite clastics. Corresponding, dolomite has five types of formation mechanism, including parasyngenetic dolomitization, mixed dolomitization, buried dolomitization, diagenetic dolomitization and weatheringtransportation of external dolostone. The effective dolomiticrock reservoirs whose space is microfissure, include dolomiticsiltstone, dolomiticmudstone, muddy dolomite, and so on. Development degree and dispositional relationship of fissure and karst cave have an important impact on the level of capacity. Overall, the microand macrodistribution characteristics of different types of dolomite are different, and their superimposed effect controls the whole features of the present dolomite.