Abstract: It is beneficial for exploitation and exploration of coal resources and resources relating to coal to analyze developing strata and distribution of coal seam in sequence stratigraphy. The time that sequence stratigraphy began to use in coal strata was 90's of last century, Diessel firstly established coal accumulation model in classical sequence stratigraphy framework, then Bochacs and Stuer discussed the change of ratio of accommodation rate/peat production rate and concretely analyzed thickness, continuity, configuration of coal seam in different accommodation. Based on studied development and distribution of coal seam in sequence stratigraphy, most coal geologists think that thick coal seams were mostly developed during late low stand-early transgression and late transgression-early high stand periods. Extremely thick coal seam is composed of many para-sequence and interface of para-sequence, so we can not easily believe extremely thick coal seam is interface of genetic stratigraphy, but we can use index of coal petrology and geochemistry to finely divide extremely thick coal seam and to confirm interface of genetic stratigraphy. In China, coal geologists studied paralic coal seam and raised ideas of coal formation in the transgressive event and coal accumulation during a lag time of marine limestone beds, and that let idea of coal accumulation in sequence stratigraphy to develop.