Abstract: The southern margin of Junggar basin is rich in low?rank coal resources. This paper reveals the sequence structure and coal?forming environment and coal accumulating regularities of the coal?bearing rock series in this area, through the outcrop observation and the core, drilling, logging data analyses, using the correlations between the base level cycle and accommodation space, by means of lithofacies paleogeographic researches, as follows: the coal?bearing rock series can be divided into five Class?III sequences and 15 system tracts from the bottom up; fan delta, delta and lake facies are the main sedimentary systems, and the sedimentary facies, subfacies and microfacies in each system show regular changes from the mountains to the basin, in which flood plain swamp, fan delta plain swamp and lakeshore swamp in inter?fan deltas are the major coal?forming microenvironments; the ancient landform and ancient sedimentary environment determine the macroscopic distribution and development degree of coal seams in the studied area, and thick coal seams are mainly developed in lowstand and highstand system tracts