Dolomite reservoir of the Permian Maokou Formation is a new realm for gas exploration in Puguang area, northeastern Sichuan Basin. Based on well cores and thin sections, it is shown that there mainly developed limy fine-grained dolomite, and locally sandy dolomite and coarse-grained dolomite, and the fine-grained dolomite is mostly semi-automorphic or automorphic with residual intergranular pore or fractures. Vertically, dolomite mainly developed at Maokou Member-2 and the top of Maokou Member-1. The total dolomite thickness of Maokou Member-2 in well Ming-1 is 18.1m, which is higher than the average about 10m. Horizontally, the dolomites mainly distributed in Shuangshimiao anticline and Dongyuezhai anticline, following by Qingxichang anticline and Xuanhandong anticline. Affected by both sedimentation and fracture system, it is concluded that the dolomite mainly developed at the shoal of inner platform where two sets of faults with different strike (NE, NW) crossed. This study would be helpful for the next gas exploration of Maokou Formation in Puguang area.