Abstract: Based on the review of the sedimentology research history of coal-bearing strata,both the sequence stratigraphy method of coal-bearing strata and the relationship between sealevel change and coal accumulation are expounded.It is emphasized that the thick,extensively distributed coal seams were actually formed in the process of base level or sea level rise.The bottom of coal seam is a marine flooding surface.The paleosols (rooting clays) underneath the coal seams or the discontinuous surface represent the exposure events which discriminate between the underlying prograding sediments and the overlying transgressive ones.