The Permian strata on the western margin of Ordos belong to strata of the pre-foreland basin. On the whole, the tectonic belts of foreland basin regionally control the diagenesis of sandstone, with different belts characterized by different diagenetic dynamical environments. The Permian high quality reservoir was formed in the western thrust belt and underwent weak compaction with shallow burial and dissolution. The sandstone pores of Permian strata on the slope belt are mainly composed of secondary pores resulting from strong dissolution, with a certain quantity of relict original pores. Great losses of sandstone original pores in the geotectogene resulted from the compaction and cementation with deep burial, whereas the reservoir quality was improved by dissolution and the sandstones served as the effective gas reservoir.