Abstract: The understandings for sedimentary environment of Paleogene Huangxian Formation in Huangxian basin are different,or suggesting it as inland fresh water lacus,or considering it as coastal lagoon.The sedimentary systems and facies associations of Huangxian Formation were studied with the help of principles and methodolohy of basin analysis.The results show that the Huangxian basin was a paralic transgressive lagoon in Paleogene,The development and allocation of sedimentary systems influenced by both transgressions and the basin-margin faults distributed regularly in the basin.The coal accumulation occurred at the intensive stage after transgression.The fan-delta and submerged fan front are favorable for coal accumulation.