Abstract: With application of rock thin section, cast thin section and SEM data analysis, using statistical methods, Shanxi formation Shang Ⅰ reservoir characteristics of Erdos basin is studied. Research results show that: the change of sedimentary facies in this area is the main influence factor to the the sand body physical property. The sand body under different sedimentary facies showed different petrologic characteristics, different diagenesis characteristics have different reservoir space characteristics and reservoir physical property, and pore structure is the concrete form of the sand body physical property.