College of Earth Sciences��Jilin University��Changchun 130061��China

Through the methods of rock slide identification��SEM��petro-physical analysis��clastic diagenesis and its influence on physical properties in the Late Permian Linxi Formation in Linxi area��Inner Mongolia have been systematically studied�� The results show that clasolite diagenesis in this area has experienced compaction��ce- mentation��metasomatism and dissolution�� The three types of sandstone cements are argillaceous��siliceous and car- bonate cements�� Argillaceous cement appears the most and mainly composed of illite��the second is chlorite�� Car- bonate cement is mainly calcite�� The main ingredient of siliceous cement are quartz secondary enlargement and au- thigenic quartz microlite�� Vitrinite reflectance (��o)��content of S% in mudstone illite/smectite (I/S)��quartz secondary enlargement level��particle contact type��illite crystallinity and some other data show that Linxi Formation clastic rocks in Linxi area is in the late diagenetic stages�� The physical properties of reservoir is closely related to diagenesis�� Compaction and cementation make porosity and permeability in Linxi area lower��while dissolution makes porosity higher��