Jiaxian—Zizhou Area with the area of 9 000 km2 is located of the eastern in Ordos basin. It one of the key regions for recent natural gas exploration. Taiyuan, Shanxi and Xiashihezi Formations in the Carboniferous and Permian are the main objective exploration targets for clastic rocks in this area. The reservoir is of characteristics of many genetic types, rock types，reservoir interspace types, as well as low porosity and low permeability. Sedimentation, diagenesis and structural process had played important roles in the formation and evolution of reservoir. Sedimentation controlled the development and distribution of reservoir, and affected basic configuration of reservoir as well as the diagenesis style and intension, which results in the change of granularity, lithology and sedimentary microfacies. Diagenesis decided the interior reservoir space and the reservoir capability. compaction and cementation are favourable process for diagenesis, while dissolution and alteration with recrystallization are on the contrary. The comprehentive evaluation using the Fuzzy theory shows that the reservoirs in the tidal channel sand bodies and the deltaic channel sand bodies are of superior capability. The blocks of Zhenchuanpu, Dafusi, Jiaxian and Zizhou are favourable exploration targets.