Abstract: Based on the drilling data, core data and seismic information, this paper discusses about features of coal-accumulating environment and coal-forming of Yacheng formation in Qiongdongnan basin with application of methods and theories of sequence stratigraphy and sedimentology. Coal seams of the Yacheng formation are mainly found in peat flat of supralittoral zone and intertidal zone of tidal flat, peat swamps of the braided river delta plain and fan-delta plain. Focusing on the coal-accumulating environment and considering the influence of paleostructure, the coal-accumulating model for Qiongdongnan basin is developed as following: the supralittoral zone and intertidal zone in tidal flat are of the largest area, being the main coal-accumulating environment; the distribution of coal-forming sedimentary system in gentle slope zones is broader than that in steep slope zones controlled by faults; the second member of Yacheng formation is of greater potentiality of coal-accumulating.

Key words: Qiongdongnan basin, Yacheng formation, coal-accumulating environment feature, coal-forming model