The studied results of regional geology, seismic, logging and core analysis data in the J1b1 sedimentary microfacies of the Badaowan Formation in the Di-12 wellblock of Dishuiquan oilfield located in slope area of eastern Junggar Basin show that the J1b1 is alluvial fan deposit, which could be further divided into 3 sub-facies of the top fan, middle fan, edge fan and 8 microfacies. The vertical variation of lithology and lithofacies reflect that the target zone with the backfill characteristic on the Carboniferous is the earliest low-stand system tract of the Jurassic in this study area. The sedimentary environment of the J1b1 is transited from the top, middle fans up to the edge fan, showing such a period is in retrograding alluvial fan deposit under transgression environment.