The clay mineral content is high in tight sandstone of Taiyuan Formation in Block Linxing of Ordos Basin，and it is one of the important factors influencing reservoir properties. However，its characteristics and formation mechanism have not been systematically studied，affecting the description of high-quality reservoirs. According to core observation，thin section identification，X-ray diffraction and physical property analysis，the content and morphological characteristics of the clay minerals is clarified. Moreover，its formation mechanism and the relationships between the clay minerals and the reservoir physical properties are discussed. The results indicate that the relative contents of clay minerals in tight sandstone of Taiyuan Formation in Block Linxing from high to low are：illite，kaolinite，chlorite，and illite-montmorillonite mixed-layer.Most of them fill in the intergranular dissolution pores or intercrystalline micropores. Hot water erosion is the reason for the clay mineral formation. Zijinshan pluton affects the relative content and plane distribution of clay minerals. The relative contents of illite，kaolinite，chlorite，and illite-montmorillonite mixed-layer are high near Zijinshan pluton，while the relative content of kaolinite is low. There exists a negative correlation between reservoir physical properties and the three types of clay minerals，including illite，chlorite，and illite-montmorillonite mixed-layer，while there is a positive correlation between kaolinite and reservoir physical properties. Influenced by clay minerals，the high-quality reservoirs distribute in the northeast and southwest of the study area，and they are the favorable targets for the later exploration and development.