Abstract: Clay minerals are closely related to shale gas. Absorption of clay minerals highly affects the enrichment of organic matters and clay minerals act as catalyst in conversion process of organic matter into hydrocarbon. Types of clay minerals affect the distribution of absorbed shale gas. In conversion process of smectite into illite, reduction of unit structural height (d0) of smectite causes structural subsidence and micro?fractures in the shale, which can provide migration path and accumulation space for shale gas. Meanwhile, precipitated interlayer water molecules serve as carrier for shale gas migration and accumulation. Among six basic modes of vertical distribution of clay minerals in petroliferous basins in China, the vertical conversion stage of normal conversion Ia subtype clay minerals has a good correlation with the organic matter evolution stage and the compaction stage, such as the Paleogene strata of most of depressions in Bohai Bay, Beibwan and Subei basins and the Cretaceous strata of most of depressions in Songliao and Erlian basins, which are all favorable for generation and enrichment of shale gas. Meanwhile, the major enriched status of shale gas in each conversion stage of clay minerals in the range of Ia subtype distribution can be predicted